Lean tissue mass measurements by dual-energy X-ray absorptiometry and associations with strength and functional outcome measures in facioscapulohumeral muscular dystrophy

Facioscapulohumeral muscular dystrophy (FSHD) is a slowly progressive disease of skeletal muscle. Dual energy X-ray absorptiometry (DEXA) is a widely available, cost-effective and sensitive technique for measuring whole body and regional lean tissue mass and has been used in prior clinical trials in neuromuscular diseases. The Clinical Trial Readiness to Solve Barriers to Drug Development in FSHD (ReSolve) study is a prospective, longitudinal, observational multisite study. We obtained concurrent DEXA scans and functional outcome measurements in 185 patients with FSHD at the baseline visit. We determined the associations between lean tissue mass in the upper and lower extremities and corresponding clinical outcome measures. There were moderate correlations between upper and lower extremity lean tissue mass and their corresponding strengths and function. Lean tissue mass obtained by DEXA scan may be useful as a biomarker in future clinical trials in FSHD.

Update on laparoscopic, robotic, and minimally invasive vaginal surgery for pelvic floor repair

Advanced laparoscopic surgery marked the beginning of minimally invasive pelvic surgery. This technique lead to the development of laparoscopic hysterectomy, colposuspension, paravaginal repair, uterosacral suspension, and sacrocolpopexy without an abdominal incision. With laparoscopy there is a significant decrease in postoperative pain, shorter length of hospital stay, and a faster return to normal activities. These advantages made laparoscopy very appealing to patients. Advanced laparoscopy requires a special set of surgical skills and in the early phase of development training was not readily available. Advanced laparoscopy was developed by practicing physicians, instead of coming down through the more usual academic channels. The need for special training did hinder widespread acceptance. Nonetheless by physician to physician training and society training courses it has continued to grow and now has been incorporated in most medical school curriculums. In the last few years there has been new interest in laparoscopy because of the development of robotic assistance. The 3D vision and 720 degree articulating arms with robotics have made suture intensive procedures much easier. Laparosco-pic robotic-assisted sacrocolpopexy is in the reach of most surgeons. This field is so new that there is very little data to evaluate at this time. There are short comings with laparoscopy and even with robotic-assisted procedures it is not the cure all for pelvic floor surgery. Laparoscopic procedures are long and many patients requiring pelvic floor surgery have medical conditions preventing long anesthesia. Minimally invasive vaginal surgery has developed from the concept of tissue replacement by synthetic mesh. Initially sheets of synthetic mesh were tailored by physicians to repair the anterior and posterior vaginal compartment. The use of mesh by general surgeons for hernia repair has served as a model for urogynecology. There have been rapid improvements in biomaterials and specialized kits have been developed by industry. The purpose of this article is to present an update in urogynecologic laparoscopy, robotic surgery, and minimally invasive vaginal surgery.

Isomer-selective adsorption of amino acids by components of natural sediments

We present evidence that under circumstances of low pH and organic-free surfaces an ordinary estuarine sediment can exhibit strong optical isomer selectivity in its absorption of a number of amino acids. This selectivity can also be seen to a lesser degree in the minerals quartz, montmorillonite, and kaolin. Adsorption reactions were performed with racemic amino acid mixtures, and after equilibrium, deviations from a D/L ratio of 1 were measured and in many cases were found to be significant. This was particularly pronounced at pH 4.0, where selective removal of the L isomers by adsorption onto sedimentfractions was almosttotal. Changes in both the nature and degree of selectivity were also observable in different sediment size fractions. While we are at this stage unable to identify the mode of primary selectivity, adsorption experiments with these candidate sediment components, quartz, kaolin, and montmorillonite do exhibit some selective behavior. We believe that the existence of natural chirally selective components in sediment may indicate a new approach to the development of chiral catalysis and synthesis.

Nicotinic regulation of c-fos and osteopontin expression in human-derived osteoblast-like cells and human trabecular bone organ culture

Long-term in vivo studies have highlighted smoking as a risk factor in postmenopausal osteoporosis, bone fracture incidence, and increased nonunion rates. In contrast, there are few data postulating the effects of smoking at the cellular level in human skeletal tissue. In this study, we present novel evidence demonstrating that the nicotinic receptor alpha4 subunit is present in human primary bone cells by using reverse transcriptase-polymerase chain reaction (RT-PCR). In addition, we demonstrate direct cellular effects of nicotine on primary human bone cells and blockage of these effects with a nicotinic receptor antagonist, D-tubocurarine. Nicotine effects on cell proliferation were biphasic with toxic, antiproliferative effects at high levels of nicotine (>1 mmol/L) and stimulatory effects at very low levels (0.01-10 micromol/L) after 72 h. This nicotine-induced increase in cell proliferation was inhibited in a dose-dependent manner by the addition of D-tubocurarine. In addition, proliferation effects from low-level treatment correlated with an upregulation of expression of the AP-1 transcription factor, c-fos, within 1 h, which was blocked by incubation with D-tubocurarine. To determine in situ bone cell responses within their trabecular matrix, cores of human bone isolated from biopsies were perfused with 0.1 micromol/L nicotine for 24 h. Western analysis of proteins isolated from the cores highlighted an increase in osteopontin, a bone matrix protein implicated in regulating resorption, which was partially inhibited by the addition of D-tubocurarine. To conclude, our results suggest that nicotine has a direct effect on human bone cells in modulating proliferation, upregulation of the c-fos transcription factor, and the synthesis of the bone matrix protein, osteopontin.

Hormonally-regulated expression of voltage-operated Ca(2+) channels in osteocytic (MLO-Y4) cells

Voltage operated calcium channels (VOCCs) are important in stimulus-response coupling in osteoblasts. We have investigated the expression of VOCCs in the mouse osteocyte cell line, MLO-Y4. Using the whole-cell patch clamp technique we were unable to detect any VOCC currents (n = 436) even in the presence of the L-type VOCC agonist Bay K 8644 (n = 350). Reverse transcription polymerase chain reaction (RT-PCR), using primers to detect alpha(1C), alpha(1D), and alpha(1G) VOCC subunits (all of which are expressed in primary osteoblasts), did not generate detectable products with mRNA from MLO-Y4 cells. However, after treatment with physiological levels of hormones, VOCC alpha(1) subunit mRNAs were detected in MLO-Y4 cells. PTH, 17beta-estradiol, and dexamethasone-treatment induced expression of L-type (alpha(1C), alpha(1D)) subunit transcripts. ATP-treatment induced expression of T-type (alpha(1G)) transcripts. Using whole-cell patch clamp we detected VOCC currents in 5-10% of cells after treatment. Current characteristics (L- or T-type) were consistent with the transcript expressed.

Three types of K(+) currents in murine osteocyte-like cells (MLO-Y4)

Osteocytes play an important role in signaling within bone. Communication of osteocytes with each other and with bone lining cells may have a function in mineral homeostasis and mechanotransduction. However, very little is known of the expression of ion channels in these cells. Using the whole-cell patch-clamp technique, we have detected three types of K(+) currents in the mouse osteocyte-like cell line MLO-Y4. The most commonly observed current (48% of cells) activated rapidly (20 msec) in response to depolarizing steps from -40 mV and exhibited voltage-dependent inactivation. The current was inhibited by 20 mmol/L tetraethyl ammonium (TEA) and abolished by intracellular 2 mmol/L 4-aminopyridine (4-AP). Biophysical and pharmacological characteristics of the current differed from those of inactivating K(+) currents in osteoblastic cells. In 22% of cells, a slowly activating, voltage-activated current was observed (threshold at 20-30 mV). This current was TEA insensitive, was abolished by intracellular application of 2 mmol/L 4-AP, and was strongly inhibited by apamin, a selective inhibitor of small conductance (SK) Ca(2+)-activated K(+) channels. A third current developed during whole-cell dialysis (37% of cells). This current showed little voltage sensitivity. It was abolished by intracellular application of 2 mmol/L 4-AP, high-extracellular Ba(2+) (108 mmol/L), or by inclusion of ATP in the intracellular solution, but was insensitive to TEA, apamin, Cs(+), and glibenclamide. None of these currents was affected by replacement of chloride with acetate in the bath or pipette salines. Reverse-transcription polymerase chain reaction confirmed the presence of mRNA for the types 1 and 2 SK channels, but message for the large conductance (BK) Ca(2+)-activated K(+) channel was not detected in these cells. Message for the sulphonylurea receptor SUR2, a subunit of glibenclamide-insensitive ATP-dependent K(+) channels (K(ATP)), was also detected, but the glibenclamide-sensitive SUR1 subunit was not. These data are the first descriptions of SK- and ATP-sensitive, glibenclamide-insensitive channels in cells of osteoblastic lineage. Our findings are consistent with a change in K(+) channel expression during differentiation from osteoblast to osteocyte. K(+) channels of osteocytes will contribute to maintenance of the cell membrane potential and thus may participate in mechanosensitivity and osteocyte intercellular communication. In addition, they may be involved in homeostatic maintenance of the extracellular fluid occupying the periosteocytic space.

Calcium-channel activation and matrix protein upregulation in bone cells in response to mechanical strain

Femur-derived osteoblasts cultured from rat femora were loaded with Fluo-3 using the AM ester. A quantifiable stretch was applied and [Ca(2+)]i levels monitored by analysis of fluorescent images obtained using an inverted microscope and laser scanning confocal imaging system. Application of a single pulse of tensile strain via an expandable membrane resulted in immediate increase in [Ca(2+)]i in a proportion of the cells, followed by a slow and steady decrease to prestimulation levels. Application of parathyroid hormone (10(-6) M) prior to mechanical stimulation potentiated the load-induced elevation of [Ca(2+)]i. Mechanically stimulating osteoblasts in Ca(2+)-free media or in the presence of either nifedipine (10 microM; L-type Ca(2+)-channel blocker) or thapsigargin (1 microM; depletes intracellular Ca(2+) stores) reduced strain-induced increases in [Ca(2+) ]i. Furthermore, strain-induced increases in [Ca(2+)]i were enhanced in the presence of Bayer K 8644 (500 nm), an agonist of L-type calcium channels. The effects of mechanical strain with and without inhibitors and agonists are described on the total cell population and on single cell responses. Application of strain and strain in the presence of the calcium-channel agonist Bay K 8644 to periosteal-derived osteoblasts increased levels of the extracellular matrix proteins osteopontin and osteocalcin within 24 h postload. This mechanically induced increase in osteopontin and osteocalcin was inhibited by the addition of the calcium-channel antagonist, nifedipine. Our results suggest an important role for L-type calcium channels and a thapsigargin-sensitive component in early mechanical strain transduction pathways in osteoblasts.

Factors influencing the total mercury and methyl mercury in the hair of the fishermen of Kuwait

Total and methyl mercury (MeHg) levels in the hair of fishermen are described anticipating that they represent the critical group for dietary exposure. One-hundred human hair samples were collected from fishermen (Egyptians: age range 25-60), living in Doha Fishing Village, Kuwait. Thirty-five additional samples were taken from a control group working in a local construction company (age range 26-35). Overall mean concentrations in the hair of the population of fishermen are 4.181+/-3.220 and 4.025+/-3.130 microg g(-1) for total and MeHg, respectively. The equivalent values for the control are 2.617+/-1.404 and 2.556+/-1.391 microg g(-1) for total and MeHg, respectively. MeHg concentrations are strongly correlated to those of total Hg ( [Formula: see text], [Formula: see text] ) and MeHg concentrations in human hair are unrelated to age and duration of residence in Kuwait but show a positive correlation with the quantity of fish consumed. Levels of Hg in hair also show a tendency to increase in those who prefer to eat the entire fish, including the heads. In general, the concentrations of total and MeHg in fishermens' hair are twice the WHO 'normal' level (2.0 microg g(-1)) but are still less than the WHO threshold level (10.0 microg g(-1)). The results also show that grey hair contains undetectable amounts of Hg and therefore does not reflect individual exposure to this contaminant.

Osteoblasts derived from load-bearing bones of the rat express both L- and T-like voltage-operated calcium channels and mRNA for alpha 1C, alpha 1D and alpha 1G subunits

Voltage operated calcium channels (VOCCs) are implicated in osteoblastic mechano- and hormonal transduction. Very little, however, is known about the expression of VOCCs in osteoblasts of load-bearing bones. Here we describe two types of whole-cell calcium current in rat femoral explant-derived osteoblasts. The first is high-voltage activated and sensitive to nifedipine, Bay K8644 and FPL 64176. The second is low-voltage activated and is sensitive to micromolar concentrations of Ni2+. The properties of these two currents are consistent with those of L-type and T-type calcium currents respectively. T-type currents were detected in most cells on the day of passage, the level of expression being significantly lower on subsequent days. L-type currents were also most common on the day of passage but were detected consistently throughout the 4-day period of study. The reverse transcription polymerase chain reaction with non-specific primers directed against all L-type VOCC alpha 1 subunits and then with specific primers directed against sequences from rat brain alpha 1C (L-type), alpha 1D (L-type) and alpha 1G (T-type) VOCC subunits detected transcripts of appropriate size in all four cases. Products from the three sets of specific primer pairs (alpha 1C, alpha 1D, alpha 1G) were sequenced and were identical to their respective rat brain templates.

Mechanotransduction pathways in bone: calcium fluxes and the role of voltage-operated calcium channels

Changes in strain distribution across the vertebrate skeleton induce modelling and remodelling of bone structure. This relationship, like many in biomedical science, has been recognised since the 1800s, but it is only the recent development of in vivo and in vitro models that is allowing detailed investigation of the cellular mechanisms involved. A number of secondary messenger pathways have been implicated in load transduction by bone cells, and many of these pathways are similar to those proposed for other load-responsive cell types. It appears that load transduction involves interaction between several messenger pathways, rather than one specific switch. Interaction between these pathways may result in a cascade of responses that promote and maintain bone cell activity in remodelling of bone. The paper outlines research on the early rapid signals for load transduction and, in particular, activation of membrane channels in osteoblasts. The involvement of calcium channels in the immediate load response and the modulation of intracellular calcium as an early signal are discussed. These membrane channels present a possible target for manipulation in the engineering of bone tissue repair.

Gas/particle partitioning behaviour of azaarenes in an urban atmosphere

The gas/particle partitioning of azaarenes in the Liverpool urban atmosphere was measured from May 1995 to April 1996. This period included one of the hottest summers and coldest winters recorded in the UK. The changes of the relative proportions of particulate and vapour phases showed a strong seasonal variation in which over 80% of azaarene compounds are associated with the particles in the winter and over 60% of azaarene compounds exist as vapour phase during the summer. The results are fitted into a gas/particle partitioning equation. Calculated vapour pressures, vaporization and desorption enthalpies are also given. Azaarene partitioning behaviour is modelled at a variety of aerosol concentrations and over a temperature range which includes normal ambient temperatures. It is hypothesised that three ring azaarene species are more likely to undergo changes in the relative proportions of particle and vapour phase material than either two or four ring compounds.

Expression of voltage-operated Ca2+ channels in rat bone marrow stromal cells in vitro

The expression of voltage-operated Ca2+ currents (VOCCs) in bone marrow stromal cells cultured for 3-30 days has been studied by the use of the whole-cell patch-clamp technique. Both low-voltage-activated (LVA) and high-voltage-activated (HVA) VOCCs were recorded. LVA currents were first detectable after 6-7 days in culture and reached a peak of expression at 8 days, after which both the amplitude and frequency of expression of the current fell rapidly. The current was virtually undetectable in cells cultured for more than 15 days. The HVA current was detectable after 3 days in culture and reached a peak of both amplitude and frequency of expression after 1-2 weeks. This current was expressed consistently throughout the remaining culture period. In cultures treated with dexamethasone (10(-8) mol/L) peak expression of LVA currents still occurred at 7-8 days, but currents were enhanced approximately threefold. Expression of LVA currents was maintained to the end of the culture period. Expression of HVA currents was not significantly modified by treatment of cultures with dexamethasone. Examination of the biophysical and pharmacological (blockade by Ni2+ and diphenylhydantoin) properties of the LVA current in these cells suggests that they may have similarities with the LVA T currents of neuronal cells.

Voltage-dependent potentiation of low-voltage-activated Ca2+ channel currents in cultured rat bone marrow cells

1. The whole-cell patch-clamp technique was used to study Ca2+ channel currents in stromal cells of 7-10 day dexamethasone-treated and control rat bone marrow cultures. In saline containing either 108 mM Ba2+ or a 2.5 mM Ca(2+)-1 mM Mg2+ mixture, most cells expressed both fast-inactivating, low-voltage-activated (LVA) and slow-inactivating, high-voltage-activated (HVA) currents. 2. Repeated application of 400 ms voltage steps to 60 mV above the holding potential (Vh, -90 mV in Ca(2+)-Mg2+ mixture and -60 mV in Ba2+) at a frequency > or = 0.1 Hz resulted in a potentiation of the LVA component of the 2nd and subsequent currents. 3. LVA current potentiation was examined using a two-pulse (prepulse-test pulse) method. Prepulses to Vh + 150 mV induced an 80-100% increase in the amplitude of the LVA component of Ca2+ channel currents in saline containing either Ba2+ or Ca(2+)-Mg2+. This effect was also seen in non-dexamethasone-treated cultures. 4. Potentiation was not modified by omission of ATP and GTP from the pipette saline, and was not inhibited by extracellular application of the broad spectrum kinase inhibitors H-7 or RK252-a. 5. Potentiation was dependent on the amplitude and duration of the prepulse. Using the standard protocol, the threshold for potentiation was approximately Vh + 45 mV and saturation occurred at Vh + 150-180 mV. Further increases in prepulse amplitude did not modify potentiation. With a prepulse to +10 mV (Ba2+ saline) potentiation was half-maximal with a prepulse duration of 250-300 ms duration and saturated at 750-1000 ms. 6. Peak potentiation occurred 1-2 s after the prepulse. The time for total decay of potentiation varied from 10 to 90 s. 7. Voltage dependency of prepulse-induced potentiation did not resemble that of inactivation induced by similar prepulses. 8. Current kinetics, I-V relationship and sensitivity to blockade by Ni2+ and diphenylhydantoin of prepulse-recruited current resembled those of control LVA current. 9. The amplitude of prepulse-recruited current was positively correlated with control LVA current amplitude. 10. LVA currents supported regenerative potentials under current clamp. Repeated activation reduced spike latency. 11. It is suggested that current potentiation may be recruited physiologically, possibly in association with activation of stretch-sensitive channels, causing enhanced activation of HVA Ca2+ currents.

The associations of linear alkyl benzenes with the bulk properties of sediments from the River Mersey Estuary

The concentration distributions of linear alkyl benzenes (LAB) are reported as a function of sediment grain size and organic-carbon and lipid concentration for samples from three sites from the River Mersey Estuary, UK. There is not a simple relationship between contaminant concentration and grain size because the contaminant burden is much more strongly related to the organic-carbon and lipid content. This association between LAB, lipid, and organic carbon can be understood in terms of a simple model in which a proportion of LAB is introduced to the bulk material at source, with the remainder being adsorbed into particle surfaces after discharge. LAB concentrations in the Mersey Estuary are relatively high, and the compounds show evidence of degradation that arises from the high level of bacterial activity within the system.

Phthalate ester speciation in estuarine water, suspended particulates and sediments

Following earlier work (Al-Omran & Preston, 1987) in which phthalate ester speciation was examined in laboratory studies, the present paper describes the results of an attempt to validate the results by field measurements in the River Mersey Estuary, Liverpool, UK. Samples of water, suspended solids and sediments were analysed for their phthalate ester content. Solid samples were also analysed for their carbon, organic carbon and lipid content. A comparison of the field and laboratory results confirms the association between diethylhexyl phthalate and small particles and shows that other phthalates tend to be associated with relatively coarse, lipid-rich particles. Partition coefficients between dissolved phthalate esters and suspended particles are calculated and compared with other laboratory studies.

The interactions of phthalate esters with suspended particulate material in fresh and marine waters

The behaviour of six phthalate esters in the presence of particulate material suspended in fresh and saline water has been examined. The adsorption of all phthalates by the particulates is enhanced by the presence of salt. The adsorption process is fairly rapid ( <2-3 h) and the degree of adsorption depends on the characteristics of the particulates. Di-ethylhexyl phthalate is adsorbed most actively by material of a small particle size. The adsorption of other phthalates is more strongly influenced by the chemical composition of the particulates and is most closely correlated with their lipid content.