Dietary supplementation with nacre reduces cortical bone loss in aged female mice

Aging is associated with detrimental bone loss leading to fragility fractures in both men and women. Notably, a majority of bone loss with aging is cortical, as well as a large number of fractures are non-vertebral and at the non-hip sites. Nacre is a product of mollusks composed of calcium carbonate embedded in organic components. As our previous study demonstrated the protective effect of nacre supplementation on trabecular bone loss in ovariectomized rats, we sought to evaluate the effect of dietary nacre on bone loss related to aging in female mice which do not suffer true menopause as observed in women. The current study compared the effect of a 90-day long nacre-supplemented diet to that of Standard or CaCO3 diets on both bone mass and strength in 16-month-old C57BL/6 female mice. Multiple approaches were performed to assess the microarchitecture and mechanical properties of long bones, analyze trabecular histomorphometry, and measure bone cell-related gene expressions, and bone turnover markers. In the cortex, dietary nacre improved cortical bone strength in line with lower expression levels of genes reflecting osteoclasts activity compared to Standard or CaCO3 diets (p < 0.05). In the trabeculae, nacre-fed mice were characterized by a bone remodeling process more active than the other groups as shown by greater histomorphometric parameters and osteoblast-related gene expressions (p < 0.05). But these differences were not exhibited at the level of the trabecular microarchitecture at this age. Collectively, these data suggest that dietary nacre should be a potential candidate for reducing aging-associated cortical bone loss in the elderly.

Clinical and radiological characteristics of odontomas: A retrospective study of 90 cases

PURPOSE

Odontomas represent a common clinical entity among odontogenic tumors, but are not well-addressed in the Vietnamese population. The present study aimed to determine the clinical and preclinical characteristics of odontomas and associated factors in the Vietnamese population.

MATERIALS AND METHODS

This retrospective study retrieved data from histopathological diagnoses from 2 central hospitals of Odonto-Stomatology in Ho Chi Minh City, Vietnam during 2004-2017. The odontomas were classified as complex (CxOD) or compound (CpOD) subtypes. The epidemiological, clinical, and radiological characteristics of the odontomas, stratified by subtype and sex, were obtained and analyzed.

RESULTS

Ninety cases, consisting of 46 CxODs and 44 CpODs, were included. The average age of patients was 32.4 (±20.2) years. The patients with CxOD were older than those with CpOD (P<0.05). Clinically, 67% of patients showed an intraoral bone expansion. Approximately 60% of patients with CxOD exhibited a painful symptom, about 3-fold more than those with CpOD (P<0.05), whereas almost all patients with CpOD exhibited perturbations of dentition, unlike those with CxOD (P<0.05). Radiologically, CxOD was characterized by a larger dimension than CpOD in both sexes (P<0.05), and CpOD induced complications in adjacent teeth more often than CxOD (P<0.05). The development of odontoma with advancing age differed significantly in odontoma subtypes related to their pathological origins, and between the sexes, resulting from different physiological states.

CONCLUSION

The findings of this study highlight the value of clinical and radiological features of odontomas and their associated factors for the early diagnosis and adequate treatment of younger patients.

A low-cost system for monitoring pH, dissolved oxygen and algal density in continuous culture of microalgae

In a continuous and closed system of culturing microalgae, constantly monitoring and controlling pH, dissolved oxygen (DO) and microalgal density in the cultivation environment are paramount, which ultimately influence on the growth rate and quality of the microalgae products. Apart from the pH and DO parameters, the density of microalgae can be used to contemplate what light condition in the culture chamber is or when nutrients should be supplemented, which both also decide productivity of the cultivation. Moreover, the microalgal density is considered as an indicator indicating when the microalgae can be harvested. Therefore, this work proposes a low-cost monitoring equipment that can be employed to observe pH, DO and microalgal density over time in a culture environment. The measurements obtained by the proposed monitoring device can be utilized for not only real-time observations but also controlling other sub-systems in a continuous culture model including stirring, ventilating, nutrient supplying and harvesting, which leads to more efficiency in the microalgal production. More importantly, it is proposed to utilize the off-the-shelf materials to fabricate the equipment with a total cost of about 513 EUR, which makes it practical as well as widespread. The proposed monitoring apparatus was validated in a real-world closed system of cultivating a microalgae strain of Chlorella vulgaris. The obtained results indicate that the measurement accuracies are 0.3%, 3.8% and 8.6% for pH, DO and microalgae density quantities, respectively.

Organic Matrix and Secondary Metabolites in Nacre

Nacre, also called mother-of-pearl, is a naturally occurring biomineral, largely studied by chemists, structural biologists, and physicists to understand its outstanding and diverse properties. Nacre is constituted of aragonite nanograins surrounded by organic matrix, and it has been established that the organic matrix is responsible for initiating and guiding the biomineralization process. The first challenge to study the organic matrix of nacre lays in its separation from the biomineral. Several extraction methods have been developed so far. They are categorized as either strong (e.g., decalcification) or soft (e.g., water, ethanol) and they allow specific extractions of targeted compounds. The structure of the nacreous organic matrix is complex, and it provides interesting clues to describe the mineralization process. Proteins, sugars, lipids, peptides, and other molecules have been identified and their role in mineralization investigated. Moreover, the organic matrix of nacre has shown interesting properties for human health. Several studies are investigating its activity on bone mineralization and its properties for skin care. In this review, we focus on the organic constituents, as lipids, sugars, and small metabolites which are less studied since present in small quantities.

Preclinical safety study of nacre powder in an intraosseous sheep model

Objectives

The purpose of this preclinical study was to evaluate the safety, the local tissue effects and bone healing performance (osteoconduction, osseointegration) of nacre powder in a sheep intraosseous implantation model. This represents the first preclinical study to assess nacre safety and efficacy in supporting new bone formation in accordance with the ISO 10993 standard for biomedical devices.

Methods

The local tissue effects and the material performance were evaluated 8 weeks after implantation by qualitative macroscopic observation and qualitative as well as semiquantitative microscopic analyses of the bone sites. Histopathological characterisations were run to assess local tissue effects. In addition, microarchitectural, histomorphometric and histological characterisations were used to evaluate the effects of the implanted material.

Results

Nacre powder was shown to cause a moderate inflammatory response in the site where it was implanted compared with the sites left empty. The biomaterial implanted within the generated defects was almost entirely degraded over the investigated time span and resulted in the formation of new bone with a seamless connection with the surrounding tissue. On the contrary, in the empty defects, the formation of a thick compact band of sclerotic bone was observed by both microarchitectural and histological characterisation.

Conclusions

Nacre powder was confirmed to be a safe biomaterial for bone regeneration applications in vivo, while supporting bone formation.

Protective effect on bone of nacre supplementation in ovariectomized rats

Nacre has emerged as a beneficial natural product for bone cells and tissues, but its effect was only studied by gavage in the ovariectomized mouse model. We sought to assess the antiosteoporotic effect of nacre through a nutritional supplementation in the ovariectomized rat model. Sixteen‐week‐old female Wistar rats were either Sham‐operated or bilateral ovariectomized (OVX) and then fed with standard diet (Sham and OVX groups) or standard diet supplemented with either 0.25% CaCO₃ or nacre (OVX CaCO₃ and OVX Nacre group, respectively) for 28 days (n = 10/group). The bone microarchitecture was assessed at appendicular and axial bones by micro‐computed tomography (μCT). Histomorphometric analysis was performed to determine cellular and dynamic bone parameters. Bone metabolism was also evaluated by biochemical markers and gene expression levels. Nacre‐based diet prevented the OVX‐induced bone loss better than that of the CaCO₃ supplement, given the significant changes in trabecular bone volume fraction (BV/TV) both at the femoral distal metaphysis (difference, 35%; p = 0.004) and at the second lumbar spine (difference, 11%; p = 0.01). Trabecular osteoclast surfaces (Oc.S/BS) were also 1.5‐fold lower at the tibial proximal metaphysis in OVX Nacre group compared with OVX CaCO₃ group (p = 0.02)_. By principal component analysis (PCA), OVX Nacre group formed a cluster away from OVX group and with a trend closest to Sham group. These data were consistent with biological measurements demonstrating a positive profile related to nacre supplementation, which blunted an increase in serum CTX level and enhanced serum P1NP secretion 14 days post‐OVX compared with CaCO₃ supplementation. Bmp2 mRNA expression in OVX Nacre group was +1.76‐fold (p = 0.004) and +1.30‐fold (p = 0.20) compared with OVX and OVX CaCO₃ groups, respectively. We conclude that supplementation with nacre could effectively limit bone loss induced by estrogen deficiency just after OVX in rats by modulating the negative imbalance of bone turnover. © 2022 The Authors. JBMR Plus published by Wiley Periodicals LLC on behalf of American Society for Bone and Mineral Research.

P–728 Can in couples with unexplained infertility the use of a prediction model to triage assisted reproduction technology save costs?

Study question

Can in couples with unexplained infertility a prognosis-tailored management strategy, that delays treatment if natural conception prospects are good, reduce costs without affecting live-birth rate?

Summary answer

In couples with unexplained infertility, use of a prognostic tool for natural conception followed by expectant management in good-prognosis couples is cost-effective.

What is known already

Few countries have guidelines for the assessment of the likelihood of natural conception to determine access to publicly funded ART. In the Netherlands and New-Zealand, couples with unexplained infertility who have a good prognosis for natural conception are encouraged to delay starting ART. However, the cost-effectiveness of this prognosis-tailored treatment strategy has not been determined.

Study design, size, duration

We studied couples with unexplained infertility to compare a prognosis-tailored strategy to care-as-usual. In the prognosis-tailored strategy, couples were assessed using Hunault’s prediction model. In good-prognosis couples (12-months natural conception &gt;40%), outcomes without ART were modelled by censoring observations after start of ART. We then assumed that poor-prognosis couples (&lt;40% natural conception) were treated, while good-prognosis couples delayed the start of treatment for 12 months. Data for the care-as-usual model were based on real observations.

Participants/materials, setting, methods

We studied 272 couples with unexplained infertility. Costs of in vitro fertilisation (IVF) and intra-uterine insemination (IUI) were calculated based on the out-of-pocket costs and Australian Medicare costs. In a cost-effectiveness model, we compared costs and effects of both strategies.

Main results and the role of chance

The prognostic model classified 272 couples with unexplained infertility as favourable (N = 107 (39.3%) or unfavourable prognosis (N = 165 (60.7%)) for natural conception. In the prognosis-tailored strategy, the cumulative live-birth rate was 71.1% (95% CI 64.7% - 76.4%) while the number of ART cycles was 393 (353 IVF; 40 IUI). In care-as-usual strategy, the cumulative conception rate leading to live-birth for the cohort of 272 couples, who underwent a total of 398 IVF cycles and 48 IUI cycles, was 72.1% (95% CI 65.7% - 77.4%). Mean time to conception leading to live birth was 388 days in the prognosis-tailored strategy and 419 days in the care-as-usual strategy.

This translated for the 272 couples into potential savings of 45 IVF cycles and eight IUI cycles, which cost a total of AUD$ 125,817 for out-of-pocket and AUD$ 264,497 for Australian Medicare. The average cost savings per couple was AUD$ 1,435 (out-of-pocket AUD$ 463 per couple and Australian Medicare AUD$ 962 per couple). The incremental cost-effectiveness ratio, which was calculated as the total costs per additional live-births, was AUD$ 143,497 per additional live birth.

Limitations, reasons for caution

This study was limited to couples at a single IVF clinic. The modelling was also based on several key assumptions, particularly the number of fresh and frozen embryo transfer cycles for each couple.

Wider implications of the findings: Our results show that in couples with unexplained infertility the use of a prognostic model guiding the start of an IVF-treatment reduces costs without compromising live birth rates.

Trial registration number

Not applicable

A new molecular imprinted PEDOT glassy carbon electrode for carbamazepine detection

An electrochemical sensor for the detection of carbamazepine was fabricated by the electropolymerization of PEDOT on glassy carbon electrodes. Molecular imprinted polymer sites were synthesized by cyclic voltammetry on the electrodes' surfaces providing high selectivity and sensitivity towards carbamazepine molecules. Scanning electron microscopy validated the formation of the polymer. Extraction of carbamazepine from the polymer was performed by immersion in acetonitrile and validated by ultraviolet-visible spectroscopy along with cyclic voltammetry experiments comparing pre- and post-template extraction data. Further cyclic voltammetry and square-wave voltammetry tests aided in characterizing the electrodes' response to carbamazepine concentration in PBS solution with [Fe(CN)₆]^3-/4- as a redox pair/mediator. The limits of detection and quantification were found to be 0.98 x 10^-3 M and 2.97 x 10^-3 M respectively. The biosensor was highly sensitive to carbamazepine molecules in comparison to non-imprinted electrodes, simple to construct and easy to operate.

Unsupervised Clustering of HRV Features Reveals Preictal Changes in Human Epilepsy

Over a third of patients suffering from epilepsy continue to live with recurrent disabling seizures and would greatly benefit from personalized seizure forecasting. While electroencephalography (EEG) remains most popular for studying subject-specific epileptic precursors, dysfunctions of the autonomous nervous system, notably cardiac activity measured in heart rate variability (HRV), have also been associated with epileptic seizures. This work proposes an unsupervised clustering technique which aims to automatically identify preictal HRV changes in 9 patients who underwent simultaneous electrocardiography (ECG) and intracranial EEG presurgical monitoring at the University of Montreal Hospital Center. A 2-class k-means clustering combined with a quantitative preictal HRV change detection technique were adopted in a subject- and seizure-specific manner. Results indicate inter and intra-patient variability in preictal HRV changes (between 3.5 and 6.5 min before seizure onset) and a statistically significant negative correlation between the time of change in HRV state and the duration of seizures (p<0.05). The presented findings show promise for new avenues of research regarding multimodal seizure prediction and unsupervised preictal time assessment.Clinical Relevance- This study proposed an unsupervised technique for quantitatively identifying preictal HRV changes which can be eventually used to implement an ECG-based seizure forecasting algorithm.

Multimodal investigation of epileptic networks: The case of insular cortex epilepsy

The insula is a deep cortical structure sharing extensive synaptic connections with a variety of brain regions, including several frontal, temporal, and parietal structures. The identification of the insular connectivity network is obviously valuable for understanding a number of cognitive processes, but also for understanding epilepsy since insular seizures involve a number of remote brain regions. Ultimately, knowledge of the structure and causal relationships within the epileptic networks associated with insular cortex epilepsy can offer deeper insights into this relatively neglected type of epilepsy enabling the refining of the clinical approach in managing patients affected by it. In the present chapter, we first review the multimodal noninvasive tests performed during the presurgical evaluation of epileptic patients with drug refractory focal epilepsy, with particular emphasis on their value for the detection of insular cortex epilepsy. Second, we review the emerging multimodal investigation techniques in the field of epilepsy, that aim to (1) enhance the detection of insular cortex epilepsy and (2) unveil the architecture and causal relationships within epileptic networks. We summarize the results of these approaches with emphasis on the specific case of insular cortex epilepsy.

Effect of herd size on subclinical infection of swine in Vietnam with influenza A viruses

Background

Influenza A viruses of swine (IAV-S) cause acute and subclinical respiratory disease. To increase our understanding of the etiology of the subclinical form and thus help prevent the persistence of IAV-S in pig populations, we conducted active virologic surveillance in Vietnam, the second-largest pig-producing country in Asia, from February 2010 to December 2013.

Results

From a total of 7034 nasal swabs collected from clinically healthy pigs at 250 farms and 10 slaughterhouses, we isolated 172 IAV-S from swine at the weaning and early-fattening stages. The isolation rate of IAV-S was significantly higher among pigs aged 3 weeks to 4.5 months than in older and younger animals. IAV-S were isolated from 16 large, corporate farms and 6 family-operated farms from among the 250 farms evaluated. Multivariate logistic regression analysis revealed that “having more than 1,000 pigs” was the most influential risk factor for IAV-S positivity. Farms affected by reassortant IAV-S had significantly larger pig populations than did those where A(H1N1)pdm09 viruses were isolated, thus suggesting that large, corporate farms serve as sites of reassortment events.

Conclusions

We demonstrate the asymptomatic circulation of IAV-S in the Vietnamese pig population. Raising a large number of pigs on a farm has the strongest impact on the incidence of subclinical IAV-S infection. Given that only some of the corporate farms surveyed were IAV-S positive, further active monitoring is necessary to identify additional risk factors important in subclinical infection of pigs with IAV-S in Vietnam.

Electronic supplementary material

The online version of this article (doi:10.1186/s12917-016-0844-z) contains supplementary material, which is available to authorized users.

Effects of insular stimulation on thermal nociception

BACKGROUND

Electrical stimulation used for brain mapping in the postero-superior insula can evoke pain. The effects of prolonged high frequency insular stimulation on pain thresholds are unknown.

OBJECTIVE/HYPOTHESIS

Prolonged high frequency insular stimulation, by virtue of its inhibitory properties on networks, could decrease thermal nociception.

METHODS

Epileptic subjects had electrodes implanted in the insular cortex for the purpose of epileptic focus resection. Thermal and pressure nociceptive thresholds were tested bilaterally on the forearm on two consecutive days. Randomly assigned double-blind high frequency (150 Hz) insular stimulation took place for 10 min before pain testing either on the first day or on the second day.

RESULTS

Six subjects (three females; mean age of 35 years) were included. Insular stimulation increased heat pain threshold on the ipsilateral (p = 0.003; n = 6) and contralateral sides (p = 0.047; n = 6). Differences in cold pain threshold did not reach statistical significance (ipsilateral: p = 0.341, contralateral: p = 0.143; n = 6), but one subject had a profound decrease in both heat and cold pain responses. Pressure pain threshold was not modified by insular stimulation (ipsilateral: p = 0.1123; contralateral: p = 0.1192; n = 6). Two of the three subjects who had a postero-superior operculo-insulectomy developed central pain with contralateral thermal nociceptive deficit.

CONCLUSIONS

High frequency inhibitory postero-superior insular stimulation may have the potential to decrease thermal nociception. Together with previous studies, our data support the notion that the integrity of this brain region is necessary for thermal but not pressure nociceptive processing.

Structural abnormalities in patients with insular/peri-insular epilepsy: spectrum, frequency, and pharmacoresistance

SUMMARY

Between 2002 and 2010, a total of 48 patients were seen at our epilepsy clinic with insular/peri-insular cortex epilepsy. Review of their MR imaging scans revealed a neoplastic lesion in 27% of patients, a malformation of cortical development in 21%, a vascular malformation in 19%, and atrophy/gliosis from an acquired insult in 17%. MR imaging results were normal in 4 patients. Other miscellaneous findings included a case of Rasmussen encephalitis, a nonspecific insular millimetric T2 signal abnormality, a neuroepithelial cyst, and hippocampal sclerosis without MR imaging evidence of dual insular pathologic features (despite depth electrode-proven insular seizures). Refractoriness to antiepileptic drug treatment was present in 56% of patients: 100% for patients with malformations of cortical development (1.0; 95% CI, 0.72-1.0), 50.0% (0.5; 95% CI, 0.21-0.78) in the presence of atrophy/gliosis from acquired insults, 39% (0.39; 95% CI, 0.14-0.68) for neoplastic lesions, and 22.2% (0.22; 95% CI, 0.06-0.55) for vascular malformations.

Insular ischemic stroke: clinical presentation and outcome

Background

The insula is a small but complex structure located in the depth of the sylvian fissure, covered by the frontal, parietal and temporal operculum. Ischemic strokes limited to the insula are rare and have not been well studied. Our objective is to better define the clinical presentation and outcome of insular ischemic strokes (IIS).

Methods

We reviewed the institutional prospective, consecutive stroke database from two centers to identify patients with IIS seen between 2008 and 2010. We also searched the Medline database using the keywords insula(r), infarction and stroke to identify previously published IIS cases confirmed by MRI. Minimal extension to an adjacent operculum or subinsular area was accepted. Clinicoradiological correlation was performed by distinguishing IIS involving the anterior (AIC) or posterior insular cortex (PIC). We collected clinical, demographic and radiological data. The outcome was determined using the modified Rankin Scale (mRS).

Results

We identified 7 patients from our institutions and 16 previously published cases of IIS. Infarcts were limited to the AIC (n = 4) or the PIC (n = 12) or affected both (n = 7). The five most frequent symptoms were somatosensory deficits (n = 10), aphasia (n = 10), dysarthria (n = 10), a vestibular-like syndrome (n = 8) and motor deficits (n = 6). A significant correlation was found between involvement of the PIC and somatosensory manifestations (p = 0.04). No other statistically significant associations were found. IIS presentation resembled a partial anterior circulation infarct (n = 9), a lacunar infarct (n = 2) or a posterior circulation infarct (n = 2). However, most cases presented findings that did not fit with these classical patterns (n = 10). At the 6 month follow up, mRS was 0 in 8/23 (35%) patients, 1–2 in 7/23 (30%) and unknown in 8/23 (35%).

Conclusions

IIS presentation is variable. Due to the confluence of functions in a restricted region, it results in multimodal deficits. It should be suspected when vestibular-like or motor but especially somatosensory, speech or language disturbances are combined in the same patient. The outcome of IIS is often favorable. Larger prospective studies are needed to better define the clinical presentation and outcome of IIS.

A low-power high-sensitivity CMOS mixed-signal seizure-onset detector

In this paper, we present a new seizure detection algorithm and the associated CMOS circuitry implementation. The proposed low-power seizure detector is a good candidate for an implantable epilepsy prosthesis. The device is designed for patient-specific seizure detection with a one variable parameter. The parameter value is extracted from a single seizure that is subsequently excluded from the validation phase. A two-path system is also proposed to minimize the detection delay. The algorithm is first validated using MATLAB® tools and then implemented and validated using circuits designed in a standard 0.18-μm CMOS process with a total power dissipation of 7.08 μW. A total of 13 seizures from two drug-resistant epileptic patients are assessed using the proposed algorithm and resulted in 100% sensitivity and a mean detection delay of 9.7 s after electrical onset.

EEG-fMRI: adding to standard evaluations of patients with nonlesional frontal lobe epilepsy

OBJECTIVE

In patients with nonlesional frontal lobe epilepsy (FLE), the delineation of the epileptogenic zone is difficult. Therefore these patients are often not considered for surgery due to an unclear seizure focus. The aim of this study was to investigate whether EEG-fMRI can add useful information in the preoperative evaluation of these patients.

METHODS

Nine nonlesional FLE patients were studied with EEG-fMRI using a 3 T scanner. Spike-related blood oxygen level dependent (BOLD) signal changes were compared to the topography of the spikes and to PET and SPECT results if available. The structural MRIs were reviewed for subtle abnormalities in areas that showed BOLD responses. For operated patients, postoperative resection and histology were compared to BOLD responses.

RESULTS

Concordance between spike localization and positive BOLD response was found in 8 patients. PET and SPECT investigations corresponded with BOLD signal changes in 6 of 7 investigations. In 2 cases, reviewing the structural MRI guided by EEG-fMRI data resulted in considering a suspicious deep sulcus. Two patients were operated. In 1, the resected cortex corresponded with the suspicious sulcus and fMRI results and histology showed cortical dysplasia. In another, histology revealed an extended microdysgenesis not visible on structural MRI. EEG-fMRI had shown activation just adjacent to the resected pathologic area.

CONCLUSIONS

Our study provides different types of support (topography, concordance with PET and SPECT, structural peculiarities, postoperative histology) that EEG-fMRI may help to delineate the epileptic focus in patients with nonlesional frontal lobe epilepsy, a challenging group in the preoperative evaluation.

Internal/external rotation moment arms of muscles at the knee: moment arms for the normal knee and the ACL-deficient knee

Knowledge of the three-dimensional balance of loads at the knee joint is required to adequately assess the treatment and rehabilitation of the malfunctioning knee. This report focuses upon the moment arms for the knee in internal/external (IE) rotation motion. It augments prior work that defined flexion/extension moment arms. Muscle excursions and angular motion of the lower leg during IE rotation were measured in 17 fresh-frozen hemi-pelvis specimens. Moment arms were calculated as the derivatives of excursion with respect to the angle. Rotational motion was performed for the normal and anterior cruciate ligament (ACL)-deficient knee. Of the 13 muscles measured at the knee, seven were significant contributors to IE rotation: the biceps femoris long and short head externally rotate opposite the gracilis, sartorious, semimembranosis, semitendonosus and popliteus, functioning as internal rotators. Moment arm magnitudes were greatest with the knee in a flexed position (internal [external] rotators peaked at 70 degrees [90 degrees] flexion). At 30 degrees flexion, the IE rotation moment arm minima and maxima were 10.1-11.6, 6.8-9.0, 6.0-15.7, 8.2-14.1 and 0.0-10.4 mm for the semimembranosis, semitendonosus, gracilis, sartorius and popliteus, and 14.7-27.9 and 18.5-31.5 mm for the biceps femoris short and long, respectively. Moment arms for the ACL-deficient condition were significantly changed only at extremes of flexion-extension.

The sex steroid binding protein (SBP or SHBG) of human plasma: identification of Tyr-57 and Met-107 in the steroid binding site

Tyrosine-57 (Y57) and methionine-107 (M107) have been identified in the binding site of the sex steroid binding protein (SBP) (or sex hormone binding globulin) of human plasma by replacing the two amino acids with a number of residues of varying structure. Replacement of Y57 with phenylalanine resulted in a fourfold increase in the K(d) of 5 alpha-dihydrotestosterone but left the K(d) of 17 beta-estradiol unchanged. Except in two cases, no further loss in binding took place when replacing Y57 with other residues, suggesting that the phenolic group of Y57 may form a hydrogen bond with the ligand. Replacement of M107 with isoleucine increased the 5 alpha-dihydrotestosterone K(d) fourfold to a value equal to that of rabbit SBP, which contains isoleucine at the corresponding position; however, the K(d) of 17 beta-estradiol remained unchanged. Replacement of M107 with threonine resulted in a tenfold decrease in 5 alpha-dihydrotestosterone binding affinity, whereas replacement with leucine left the K(d) unchanged. These data indicate that substitutions on the beta-carbon of the amino acid side-chain at position 107 causes significant loss of binding affinity but, as in the case of Y57, the activity was not totally eliminated. We conclude that Y57 and M107 form part of a structural motif within the steroid binding site and specifically contribute binding energy to ring A of 5 alpha-dihydrotestosterone but not to ring A of 17 beta-estradiol. We also propose that the integrated contribution of several side chains may be required to optimize the ligand affinity of the steroid binding site. This proposal may fit a 'lock and key' model where little movement of the side chains occurs during binding as might be expected for a rigid structure like the steroid nucleus.

Differential toxicities of anticancer agents among DNA repair and checkpoint mutants of Saccharomyces cerevisiae

Most cytotoxic anticancer agents damage DNA directly, interfere with DNA metabolism or chromosome segregation, and are particularly toxic in dividing cells. Although a considerable amount of information on the mechanisms of action of these agents is available, the molecular bases for selective tumor cell killing by chemotherapy are largely unknown. Many genetic alterations found in sporadic and hereditary cancers affect functions in DNA repair and cell cycle control and result in sensitivity to DNA damaging agents. We have therefore set out to determine the effects of these cancer mutations on sensitivity or resistance to various chemotherapeutic agents. Because most of the affected genes are well conserved among eukaryotes, we have carried out a comprehensive analysis of a panel of isogenic yeast strains, each defective in a particular DNA repair or cell cycle checkpoint function, for sensitivity to the Food and Drug Administration-approved cytotoxic anticancer agents. Widely different toxicity profiles were observed for 23 agents and X-rays, indicating that the type of DNA repair and cell cycle checkpoint mutations in individual tumors could strongly influence the outcome of a particular chemotherapeutic regimen.

Lovastatin biosynthesis in Aspergillus terreus: characterization of blocked mutants, enzyme activities and a multifunctional polyketide synthase gene

BACKGROUND

Lovastatin, an HMG-CoA reductase inhibitor produced by the fungus Aspergillus terreus, is composed of two polyketide chains. One is a nonaketide that undergoes cyclization to a hexahydronaphthalene ring system and the other is a simple diketide, 2-methylbutyrate. Fungal polyketide synthase (PKS) systems are of great interest and their genetic manipulation should lead to novel compounds.

RESULTS

An A. terreus mutant (BX102) was isolated that could not synthesize the nonaketide portion of lovastatin and was missing a approximately 250 kDa polypeptide normally present under conditions of lovastatin production. Other mutants produced lovastatin intermediates without the methylbutyryl sidechain and were missing a polypeptide of approximately 220 kDa. The PKS inhibitor cerulenin reacted covalently with both polypeptides. Antiserum raised against the approximately 250 kDa polypeptide was used to isolate the corresponding gene, which complemented the BX102 mutation. The gene encodes a polypeptide of 269 kDa containing catalytic domains typical of vertebrate fatty acid and fungal PKSs, plus two additional domains not previously seen in PKSs: a centrally located methyltransferase domain and a peptide synthetase elongation domain at the carboxyl terminus.

CONCLUSIONS

The results show that the nonaketide and diketide portions of lovastatin are synthesized by separate large multifunctional PKSs. Elucidation of the primary structure of the PKS that forms the lovastatin nonaketide, as well as characterization of blocked mutants, provides new details of lovastatin biosynthesis.

Pain and the Guillain-Barré syndrome in children under 6 years old

During a 15-year period, 29 children, under the age of 6 years, with acute Guillain-Barré syndrome were seen at our institution. A review of their charts revealed that pain was a symptom in all patients and was present on admission in 79% of cases. Pain was often the most important symptom and led to misdiagnosis in 20 patients (69%). In 11 of these children, symptoms were present for more than a week before the correct diagnosis was made. The most common pain syndrome was back and lower limb pain, present in 83% of patients. Pediatricians should consider Guillain-Barré syndrome in their differential diagnosis when faced with a child who has lower limb pain and areflexia.

Diaschisis and neurobehavior

We review forms of diaschisis and their relationship with neurobehavioral and neuropsychological findings. The following forms of diaschisis are discussed: (1) cortico-cerebellar diaschisis; (2) cerebello-cortical diaschisis; (3) transhemispheric diaschisis; (4) cortico-thalamic diaschisis; (5) thalamo-cortical diaschisis; and (6) basal ganglia-cortical diaschisis. For each form, the neurobehavioral and neuropsychological findings are discussed. Diaschisis can be classified from the behavioral point of view as follows: (1) forms in which the metabolic effect at distance is not followed by neurobehavioral impairment; (2) forms in which the remote metabolic impairment could induce neurobehavioral and neuropsychological disorders; and (3) forms in which the role of the lesion itself and its remote metabolic effects on the production of neurobehavioral and neuropsychological abnormalities cannot be disentangled.

Muscle balance at the knee--moment arms for the normal knee and the ACL-minus knee

Forces, moments and stresses at the knee are dependent upon external and internal loading factors including muscle forces, segmental position and velocity, load carried, and the moment arms (mechanical advantage) of the muscle-tendon units. Requisite to prediction of forces and moments is a detailed understanding of effective moment arms throughout the knee range-of-motion (ROM). Existing muscle models for the knee are based upon limited static studies of only a few preserved specimens. The objectives of this report are to develop a comprehensive description of muscle-tendon moment arms for the normal knee and the anterior cruciate ligament (ACL)-minus knee during flexion-extension motion. Recent research results describe two nonorthogonal, nonintersecting axes of motion for the knee--one describing flexion-extension (FE) and the other longitudinal rotation (LR, equivalent to internal-external rotation). The effective flexion-extension moment arms of the muscles crossing the knee were developed with respect to the FE axis in 15 fresh, hemi-pelvis cadaver specimens. The normal moment arms for each of 13 muscles plus the patellar tendon exhibited variable, yet repeatable and recognizable patterns throughout the ROM. For most muscles there was no significant difference between the normal and ACL-minus moment arms. The results provide a basis for more accurate predictions of joint reaction forces and moments as well as useful knowledge for practitioners and therapists to assist in the assessment of muscle balance at the knee following injury, repair, and throughout rehabilitation.

Genetic identification of two major modifier loci of polycystic kidney disease progression in pcy mice

Unlike the uniform disease progression in inbred animals, polycystic kidney disease (PKD) progression within human families can be highly variable. This may be due to environmental or genetic factors or both. To determine if PKD severity can be influenced by modifier genes, we carried out an intercross between DBA/2-pcy/pcy and Mus m. castaneous involving 3,105 6-wk-old F2 mice. Large differences in PKD severity were observed in this cross. In addition, 23/ 800 phenotypically normal mice were pcy/pcy genotypically. These results demonstrated that PKD progression in pcy/ pcy mice is a quantitative trait that is strongly modulated by modifier genes. Whole genome quantitative trait loci mapping of 114 selected pcy/pcy mice (68 with the mild PKD and 46 with severe PKD) identified two loci, MOP1 and MOP2 that strongly modulate PKD progression. MOP1 (max LOD score = 10.3 at D4Mit111) and MOP2 (max LOD score = 13.8 at D16Mit1) accounted for 36.7 and 46.8% of the phenotypic variance, respectively. Two-factor ANOVA of the phenotypes and genotypes of all 673 pcy/pcy mice from our cross indicated that MOP1 and MOP2 alleles regulate PKD progression in a complex additive manner. Characterization of these novel modifying loci may provide additional insights into the pathogenesis of polycystic kidney diseases.

A conformational model for the human liver microsomal glucose-6-phosphatase system: evidence from rapid kinetics and defects in glycogen storage disease type 1

Rapid kinetics of glucose-6-phosphate (G6P) uptake and hydrolysis as well as of orthophosphate uptake were investigated in microsomes prepared from normal and glycogen storage disease type 1a (GSD 1a) human livers using a fast sampling, rapid filtration apparatus and were compared to those of rat liver microsomes. As shown before with rat microsomes, the production of [U-14C]glucose from 0.2 mmol/L [U-14C]G6P by untreated normal human microsomes was characterized by a burst in activity during the first seconds of incubation, followed by a slower linear rate. The initial velocity of the burst was equal to the rate of glucose production in detergent-treated microsomes. In untreated and detergent-treated GSD 1a microsomes, no glucose-6-phosphatase activity was observed. When untreated normal human or rat microsomes were incubated in the presence of 0.2 mmol/L [U-14C]G6P, an accumulation of [U-14C]glucose was observed, whereas no radioactive compound (G6P and/or glucose) was taken up by GSD 1a microsomes. Orthophosphate uptake was, however, detectable in both GSD 1a and normal untreated vesicles. These results do not support a rate-limiting transport of G6P in untreated normal human microsomes and further show that in this case of GSD 1a, no distinct G6P transport activity is present.

Inhibition of nitric oxide synthesis causes systemic and pulmonary vasoconstriction in isoflurane-anesthetized dogs

The postulate that the hemodynamic changes produced by isoflurane (1.5%) involve release of nitric oxide (NO) was examined. Fifteen dogs were anesthetized with thiamylal (15 mg/kg) and ventilated with isoflurane and oxygen. Catheters were inserted for measurement of aortic pressure, pulmonary artery pressures, and determination of cardiac output. Left thoracotomy was performed and complete heart block was induced by injection of 37% formaldehyde (0.3 mL) into the atrioventricular node; ventricular rate was fixed at 100 beats/min by external pacing. An apical microtransducer was inserted into the left ventricle (LV) via the apex for measurement of left ventricular pressure (LVP) and its first derivative (dP/dt). Flow probes were mounted on the left circumflex (Cx) and anterior descending (AD) coronary arteries. Measurements were obtained before (control period) and during NO inhibition using IV NG-nitro-L-arginine methyl ester (L-NAME) by a 50 mg/kg bolus plus 1 mg/kg/min. Infusion of L-NAME caused immediate and sustained increases in mean arterial pressure to 145 +/- 3% (P < 0.001), mean pulmonary arterial pressure to 128 +/- 5% (P < 0.001), pulmonary capillary wedge pressure to 144 +/- 8% (P < 0.001), coronary perfusion pressure to 163 +/- 4% (P < 0.001), systemic vascular resistance to 209 +/- 9% (P < 0.001), pulmonary vascular resistance to 142 +/- 12% (P < 0.005), anterior descending flow to 115 +/- 4% (P < 0.005), and circumflex flow to 113 +/- 3% (P < 0.01) of control levels.(ABSTRACT TRUNCATED AT 250 WORDS)

Site-specific suppression of cell-mediated immunity by cyclosporine

In this study, it was demonstrated that site-specific suppression of T-cell-mediated immune responsiveness could indeed be achieved by topical application of cyclosporine. Evidence for site-specific immune suppression was obtained from a dual skin allograft model in rats. These animals were given an initial 10-d systemic treatment of CsA. Subsequently, one allograft was treated with topical CsA and the other was treated with the vehicle alone. Anti-inflammatory efficacy and prolonged skin allograft survival were observed both grossly and histopathologically in the presence of topically administered CsA, while contralateral vehicle-treated control grafts underwent vigorous rejection. Systemic lymphocyte DNA synthesis following Con-A and PHA stimulation was normal to elevated. Therefore, systemic T-cell-mediated immunity appeared unaffected or possibly activated even with concomitant topical CsA treatment. CsA levels were low systemically, and showed relative site-specificity in terms of tissue concentration. In conclusion, this study indicates that topical CsA is capable of locally suppressing a strong T-cell-mediated immune response after an initial short-term systemic dose of CsA. Furthermore, certain putative autoimmune and inflammatory diseases of the skin, such as psoriasis and eczematous dermatitis, which may share common mechanisms of action compared to skin allograft rejection should likewise benefit from topical CsA treatment.