Diatom-inspired self-assembly for silica thin sheets of perpendicular nanochannels

HYPOTHESIS

Multistage silicate self-organization into light-weight, high-strength, hierarchically patterned diatom frustules carries hints for innovative silica-based nanomaterials. With sodium silicate in a biomimetic sol-gel system templated by a tri-surfactant system of hexadecyltrimethylammonium bromide, sodium dodecylsulfate, and poly(oxyethylene-b-oxypropylene-b-oxyethylene) (P123), mesoporous silica nanochannel plates with perpendicular channel orientation are synthesized. The formation process, analogous to that of diatom frustules, is postulated to be directed by an oriented self-assembly of the block copolymer micelles shelled with charged catanionic surfactants upon silication.

EXPERIMENTS

The postulated formation process for the oriented silica nanochannel plates was investigated using time-resolved small-angle X-ray and neutron scattering (SAXS/SANS) and freeze fracture replication transmission electron microscopy (FFR-TEM).

FINDINGS

With fine-tuned molar ratios of the anionic, cationic, and nonionic surfactants, the catanionic combination and the nonionic copolymer form charged, prolate ternary micelles in aqueous solutions, which further develop into prototype monolayered micellar plates. The prolate shape and maximized surfactant adsorption of the complex micelles, revealed from combined SAXS/SANS analysis, are of critical importance in the subsequent micellar self-assembly upon silicate deposition. Time-resolved SAXS and FFR-TEM indicate that the silicate complex micelles coalesce laterally into the prototype micellar nanoplates, which further fuse with one another into large sheets of monolayered silicate micelles of in-plane lamellar packing. Upon silica polymerization, the in-plane lamellar packing of the micelles further transforms to 2D hexagonal packing of vertically oriented silicate channels. The unveiled structural features and their evolution not only elucidate the previously unresolved self-assembly process of through-thickness silica nanochannels but also open a new line of research mimicking free-standing frustules of diatoms.

Hierarchically Porous Carbon Materials from Self-Assembled Block Copolymer/Dopamine Mixtures

Hierarchically porous carbon materials with interconnected frameworks of macro- and mesopores are desirable for electrochemical applications in biosensors, electrocatalysis, and supercapacitors. In this study, we report a facile synthetic route to fabricate hierarchically porous carbon materials by controlled macro- and mesophase separation of a mixture of polystyrene-block-poly(ethylene) and dopamine. The morphology of mesopores is tailored by controlling the coassembly of PS-b-PEO and dopamine in the acidic tetrahydrofuran-water cosolvent. HCl addition plays a critical role via enhancing the charge-dipole interactions between PEO and dopamine and suppressing the clustering and chemical reactions of dopamine in solution. As a result, subsequent drying can produce interpenetrated PS-b-PEO/DA mixtures without forming dopamine microsized crystallites. Dopamine oxidative polymerization induced by solvent annealing in NH₄OH vapor enables the formation of percolating macropores. Subsequent pyrolysis to selectively remove the PS-b-PEO template from the complex can produce hierarchically porous carbon materials with interconnected frameworks of macro- and mesopores when pyrolysis is implemented at a low temperature or when DA is a minor component.

A Novel Use of Umbilical Perinatal Graft in Subungual Exostosis Resection

Nail pathologies have a broad range of origin and may sometimes be complicated in presentation or clinical course, specifically when the pathology remains recalcitrant after treatment. In this case report we discuss a pathologic disorder that was initially misdiagnosed as a pyogenic granuloma surrounding an ingrown nail but was later found to be a benign neoplastic bone growth, Dupuytren exostosis, also known as a subungual exostosis. Operative treatment was deemed appropriate for the patient, and the exostosis was resected, leaving a soft-tissue void at the distal toe. The remaining void was filled with a perinatal graft, the use of which has been deemed effective anecdotally in both chronic and acute lower-extremity wounds but has not been widely discussed in the lower-extremity literature. This graft was placed to aid in wound healing over a potentially difficult wound bed. As amniotic, chorionic, and umbilical grafts become more prevalent in lower-extremity surgery, its antitumor effects should be further explored and published. This is the first case report, to our knowledge, of the successful use of a perinatal graft in the setting of a bone tumor, and it demonstrates that certain benign neoplasms can be treated with resection and placement of a perinatal graft while helping to prevent chronic wounds at surgical sites.

Maternal and fetal genetic contribution to gestational weight gain

BACKGROUND

Clinical recommendations to limit gestational weight gain (GWG) imply high GWG is causally related to adverse outcomes in mother or offspring, but GWG is the sum of several inter-related complex phenotypes (maternal fat deposition and vascular expansion, placenta, amniotic fluid and fetal growth). Understanding the genetic contribution to GWG could help clarify the potential effect of its different components on maternal and offspring health. Here we explore the genetic contribution to total, early and late GWG.

PARTICIPANTS AND METHODS

A genome-wide association study was used to identify maternal and fetal variants contributing to GWG in up to 10 543 mothers and 16 317 offspring of European origin, with replication in 10 660 mothers and 7561 offspring. Additional analyses determined the proportion of variability in GWG from maternal and fetal common genetic variants and the overlap of established genome-wide significant variants for phenotypes relevant to GWG (for example, maternal body mass index (BMI) and glucose, birth weight).

RESULTS

Approximately 20% of the variability in GWG was tagged by common maternal genetic variants, and the fetal genome made a surprisingly minor contribution to explain variation in GWG. Variants near the pregnancy-specific beta-1 glycoprotein 5 (PSG5) gene reached genome-wide significance (P=1.71 × 10-8) for total GWG in the offspring genome, but did not replicate. Some established variants associated with increased BMI, fasting glucose and type 2 diabetes were associated with lower early, and higher later GWG. Maternal variants related to higher systolic blood pressure were related to lower late GWG. Established maternal and fetal birth weight variants were largely unrelated to GWG.

CONCLUSIONS

We found a modest contribution of maternal common variants to GWG and some overlap of maternal BMI, glucose and type 2 diabetes variants with GWG. These findings suggest that associations between GWG and later offspring/maternal outcomes may be due to the relationship of maternal BMI and diabetes with GWG.

Design of wearable and wireless multi-parameter monitoring system for evaluating cardiopulmonary function

The 6-minute walking test (6MWT) is the test most commonly used to evaluate cardiopulmonary function in patients with respiratory or heart disease. However, there was previously no integrated monitoring system available to simultaneously record both the real-time cardiopulmonary physiological parameters and the walking information (i.e., walking distance, speed, and acceleration) during the 6MWT. In this study, then, a wearable and wireless multi-parameter monitoring system was proposed to simultaneously monitor oxygen saturation (SpO₂), heart rhythm, and the walking information during the 6MWT. A multi-parameter detection algorithm was also designed to estimate the heart rate effectively. The results of the study indicate that this system was able to reveal the dynamic changes and differences in walking speed and acceleration during the 6MWT. As such, the system has the potential to provide a more integrated approach to monitoring cardiopulmonary parameters and walking information simultaneously during the 6MWT. The proposed system warrants further investigation as an assistive assessment tool in evaluating cardiopulmonary function and may be widely applied in cardiopulmonary-related and sports medicine applications in the future.

Investigation of the spectral reflectance and bidirectional reflectance distribution function of sea foam layer by the Monte Carlo method

Spectral properties of sea foam greatly affect ocean color remote sensing and aerosol optical thickness retrieval from satellite observation. This paper presents a combined Mie theory and Monte Carlo method to investigate visible and near-infrared spectral reflectance and bidirectional reflectance distribution function (BRDF) of sea foam layers. A three-layer model of the sea foam is developed in which each layer is composed of large air bubbles coated with pure water. A pseudo-continuous model and Mie theory for coated spheres is used to determine the effective radiative properties of sea foam. The one-dimensional Cox-Munk surface roughness model is used to calculate the slope density functions of the wind-blown ocean surface. A Monte Carlo method is used to solve the radiative transfer equation. Effects of foam layer thickness, bubble size, wind speed, solar zenith angle, and wavelength on the spectral reflectance and BRDF are investigated. Comparisons between previous theoretical results and experimental data demonstrate the feasibility of our proposed method. Sea foam can significantly increase the spectral reflectance and BRDF of the sea surface. The absorption coefficient of seawater near the surface is not the only parameter that influences the spectral reflectance. Meanwhile, the effects of bubble size, foam layer thickness, and solar zenith angle also cannot be obviously neglected.

Wireless Monitoring System for Oral-Feeding Evaluation of Preterm Infants

The oral feeding disorder is one of the important indicators for the high risk group of neurodevelopment delay. The procedure of oral feeding requires the coordination of sucking, swallowing, and breathing activities, and it is the most complex sensorimotor process for newborn infants. Premature infants often uneasily complete the procedure of oral feeding. However, the evaluation of the oral feeding disorders and severity are usually dependent on the subjective clinical experience of the physician. Monitoring the sucking-swallowing-breathing activities directly is difficult for preterm infants. In this study, a wireless monitoring system for oral-feeding evaluation of full term and preterm infants was proposed to objectively and quantitatively evaluate the coordination of suck-swallow-respiration function during oral feeding. Moreover, the ratios of the swallowing and breathing event numbers to the sucking event number were defined to evaluate the coordination of suck-swallow-respiration function during oral feeding. Finally, the system performance was validated and the coordination of suck-swallow-respiration function for full term and preterm infants during oral feeding was also investigated.

Effects of Replacement of Fish Meal by Soy Protein Isolate on the Growth, Digestive Enzyme Activity and Serum Biochemical Parameters for Juvenile Amur Sturgeon (Acipenser schrenckii)

An 8-wk experiment was conducted to evaluate the effect of replacing fish meal (FM) with soy protein isolate (SPI) on the growth, digestive enzyme activity and serum biochemical parameters of juvenile Amur sturgeon (Acipenser schrenckii). SPI was used to replace 0, 25, 50, 62.5, 75, 87.5, 100% of dietary FM and 100% replacement supplemented crystalline amino acid. Healthy sturgeon with an average initial weight of 26.38±0.24 g were randomly assigned to 24 aquaria (8 treatments with triplicates each) at an initial stocking density of 11 fish per aquarium and cultured for 8 wks. The results showed that 75.00% or more substitution resulted in a poor weight gain rate, feed conversion ratio and survival rate compared to that of fish fed the control diet (p<0.05), whereas no significant differences were observed between diets of 25.00% to 62.50% substitution. Protease, lipase and amylase activity in foregut, mid-gut and hindgut were significantly (p<0.05) decreased by diets where SPI replacement levels were 62.50% or more. Levels of serum total protein (TP) and globulin decreased significantly from 21.03, 10.34 to 14.05, 5.63 g/L with the increasing dietary SPI (p<0.05), but alkaline phosphatase activity significantly increased (p<0.05). In addition, supplemental crystalline amino acid in the FM absence diet did not improve growth performance, intestine digestive enzyme activities and serum biochemical parameters. In conclusion, the results from this study showed adverse effects of inclusion of SPI in diets on growth performance, feed utilization and serum biochemical parameters in juvenile Amur sturgeon. Based on WGR and replacement ratio presented in this report, a 57.64% replacement level was recommended.

Rapid nongenomic effect of corticosterone on neuronal nicotinic acetylcholine receptor in PC12 cells

The effects of corticosterone, a natural glucocorticoid of rat, on the acetylcholine (ACh)-induced current (I(ACh)) were studied in pheochromocytoma (PC12) cells by using whole-cell clamp technique. The I(ACh) proved to be generated through neuronal nicotinic receptor. ACh (30 microM) induced an inward current at a holding potential of -80 mV. When cells were preincubated with corticosterone (0.1-100 microM) for 4 min, an inhibitory effect of corticosterone on the peak of I(ACh) was found. This effect was reversible, concentration-dependent, and voltage-independent. Intracellular application of corticosterone through the patch electrode did not affect the I(ACh). Extracellular application of 10 microM corticosterone neither shifted the dose-response curve of the peak I(ACh) to the right (dissociation constant (K(d)) = 16.5 microM) nor affected its coefficient (1.8) but inhibited the curve amplitudes by approximately 49% in the cells pretreated with corticosterone for 4 min. Bovine serum albumin-conjugated corticosterone (0.1-10 microM) had the inhibition similar to corticosterone. The inhibitor of transcription, actinomycin D (10 microM), and the protein synthesis inhibitor, cycloheximide (50 microM), had no effect on the inhibition induced by corticosterone on I(ACh). These results suggest that corticosterone has rapid inhibitory effect on I(ACh) in PC12 cells, which is mediated by a nongenomic mechanism. It indicates that corticosterone binds to the specific site on the outer cell membrane, probably on the neuronal nicotinic receptor-coupled channel, and inhibits the I(ACh) in a noncompetitive manner, thus controlling the immediate catecholamine release from the sympathetic cells.

Restoration of decreased N-methyl-d-asparate receptor activity by brain-derived neurotrophic factor in the cultured hippocampal neurons: involvement of cAMP

Brain-derived neurotrophic factor (BDNF) may play an important role in the modulation of N-methyl-d-asparate (NMDA) receptor function. To elucidate the underlying mechanisms, whole-cell patch-clamp recording was used to assess the effect of BDNF on the responses of cultured hippocampal neurons to the glutamate receptor agonist NMDA. We found that peak amplitude of NMDA-evoked currents in cultured hippocampal pyramidal neurons at Day 18 in vitro decreased significantly compared to that of NMDA currents at Day 10 or 14. Interestingly, NMDA-evoked currents were greatly enhanced by BDNF (50 ng/ml) in cultured neurons at Day 18, but not at Day 10 or 14. Treatment with Rp-cAMP abolished the potentiating effects of BDNF on NMDA current. Elevating the amount of cytosolic cAMP by preincubation with forskolin or Sp-cAMP also enhanced NMDA currents as effectively as BDNF in 18-day-old hippocampal neurons. Measurement of the cellular content of cAMP by RIA indicated that cultured hippocampal neurons showed decreased basal cAMP levels at the time NMDA currents were decreased and BDNF increased the decreased cAMP levels. Taken together, these results suggest that BDNF may restore decreased NMDA receptor activity in cultured hippocampal neurons by the cAMP pathway.

Calmodulin levels are dynamically regulated in living vascular smooth muscle cells

The total unbound calmodulin (i.e., not bound to target proteins) level in living smooth muscle cells from the ferret portal vein was monitored with a low-affinity, calmodulin-binding peptide tagged with an environmentally sensitive fluorophore. GS17C, a previously characterized peptide, from the calmodulin-binding domain of caldesmon was tagged with iodoacetyl nitrobenz-2-oxa-1,3-diazole (NBD) or, as a negative control, with iodoacetylfluorescein isothiocyanate. Increases in NBD-GS17C fluorescence were detected by using confocal microscopy when chemically loaded cells were stimulated with solutions of elevated [K(+)] or the calcium ionophore 4-bromoA-23187 to elicit increases in intracellular Ca(2+) concentration ([Ca(2+)](i)) quantified by fura 2. Increases in peptide fluorescence were detected in response to a phorbol ester in the absence of changes in [Ca(2+)](i). These changes were blocked by the addition of the calmodulin antagonist calmidazolium. These results suggest that the total unbound intracellular calmodulin levels may be sufficient to regulate the activity of caldesmon and, furthermore, that phosphorylation of protein kinase C substrates may increase the level of available calmodulin in living smooth muscle cells.

The major myosin-binding site of caldesmon resides near its N-terminal extreme

The primary myosin-binding site of caldesmon was thought to be in the N-terminal region of the molecule, but the exact nature of the caldesmon-myosin interaction has not been well characterized. A caldesmon fragment that encompasses residues 1-240 (N240) was found to bind full-length smooth muscle myosin on the basis of co-sedimentation experiments. The interaction between myosin and N240 was not affected by phosphorylation of myosin, but it was weakened by the presence of Ca(2+)/calmodulin. To locate the myosin-binding site, we have designed several synthetic peptides based on the N-terminal caldesmon sequence. We found that a peptide stretch corresponding to the first 27 residues (Met-1 to Tyr-27), but not that of the first 22 residues (Met-1 to Ala-22), exhibited a moderate affinity toward myosin. We also found that a peptide containing the segment from Ile/Leu-25 to Lys-53 bound both myosin and heavy meromyosin more strongly and was capable of displacing caldesmon from myosin. Our results demonstrate that the sequence near the N-terminal extreme of caldesmon harbors a major myosin-binding site of caldesmon, in which both the nonpolar residues and clusters of positively and negatively charged residues confer the specificity and affinity of the caldesmon-myosin interaction.

Calmodulin remains extended upon binding to smooth muscle caldesmon: a combined small-angle scattering and fourier transform infrared spectroscopy study

We show that calmodulin (CaM) has an extended conformation in its complexes with sequences from the smooth muscle thin filament protein caldesmon (CaD) by using small-angle X-ray and neutron scattering with contrast variation. The CaD sequences used in these experiments were a C-terminal fragment, 22kCaD, and a smaller peptide sequence within this fragment, MG56C. Each of these sequences contains the CaM-binding sites A and B previously shown to interact with the C- and N-terminal lobes of CaM, respectively [Wang et al. (1997) Biochemistry 36, 15026]. By modeling the scattering data, we show that the majority of the MG56C sequence binds to the N-terminal domain of CaM. FTIR data on CaM complexed with 22kCaD or with MG56C peptide show the 22kCaD sequence contains unordered, helix, and extended structures, and that the extended structures reside primarily in the MG56C portion of the sequence. There are small changes in secondary structure, involving approximately 12 residues, induced by CaM binding to CaD. These changes involve a net decrease in extended structures accompanied by an increase in alpha-helix, and they occur within the CaM and/or in the MG56C sequence.

Effect of forskolin on acetylcholine-induced current in rat pheochromocytoma cells

AIM

To study the effect of forskolin on the nicotinic receptor (NicR) of PC12 cells.

METHODS

The acetylcholine (ACh)-induced current (IACh) was measured on PC12 cells by whole-cell clamp technique.

RESULTS

The IACh could be blocked by d-tubocurarine chloride and atropine had no effect on IACh. Infusion of forskolin (1-50 mumol.L-1) caused an inhibition on IACh, which was reversible, concentration-dependent, and voltage-independent. Preincubation with 8-bromo-adenosine-3', 5'-adenosine monophosphate (8-Br-cAMP), a cell-permeable cAMP analog which preferentially activated cyclic AMP-dependent protein kinase (CADPK), for 20 min, did not affect the IACh and the inhibitory effect of forskolin. Infusion of 1,9-dideoxyforskolin, an analog of forskolin which did not activate adenyl cyclase, also caused an inhibition on IACh.

CONCLUSION

The inhibitory effect of forskolin on IACh in PC12 cells is not mediated by activating the adenyl cyclase. Probably, the lipophilic forskolin acts via perturbing the plasma membrane lipid structure and altering the function of the NicR.

Regulation of vascular smooth muscle tone by N-terminal region of caldesmon. Possible role of tethering actin to myosin

To assess the functional significance of tethering actin to myosin by caldesmon in the regulation of smooth muscle contraction, we investigated the effects of synthetic peptides, containing the myosin-binding sequences in the N-terminal region of caldesmon, on force directly recorded from single permeabilized smooth muscle cells of ferret portal vein. Two peptides were used, IK29C and MY27C, containing residues from Ile(25) to Lys(53) and from Met(1) to Tyr(27) of the human and chicken caldesmon sequence, respectively, plus an added cysteine at the C terminus. In cells clamped at pCa 6. 7, both peptides increased basal tone. Pretreatment of cells at pCa 6.7 with IK29C or MY27C decreased the amplitude of subsequent phenylephrine-induced contractions but not microcystin-racemic mixture-induced contractions. In all cases the effects of the peptides were concentration-dependent, and IK29C was more potent than MY27C, in agreement with their relative affinity toward myosin. The peptides were ineffective after the phenylephrine contraction was established. MY27C did not further increase the magnitude of contraction caused by a maximally effective concentration of IK29C, consistent with the two peptides having the same mechanism of action. Neither polylysine nor two control peptides containing scrambled sequences of IK29C, which do not bind myosin, had any effect on basal or phenylephrine-induced force. Our results suggest that IK29C and MY27C induce contraction by competing with the myosin-binding domain of endogenous caldesmon. Digital imaging of fluoroisothiocyanate-tagged IK29C confirmed the association of the peptide with intracellular filamentous structures. The results are consistent with a model whereby tethering of actin to myosin by caldesmon may play a role in regulating vascular tone by positioning the C-terminal domain of caldesmon so that it is capable of blocking the actomyosin interaction.

Mammal-specific, ERK-dependent, caldesmon phosphorylation in smooth muscle. Quantitation using novel anti-phosphopeptide antibodies

Extracellular signal-regulated kinases (ERKs) phosphorylate the high molecular mass isoform of the actin-binding protein caldesmon (h-CaD) at two sites (Ser(759) and Ser(789)) during smooth muscle stimulation. To investigate the role of phosphorylation at these sites, antibodies were generated against phosphopeptides analogous to the sequences around Ser(759) and Ser(789). Affinity-purified antibodies were phosho- and sequence-specific. The major site of phosphorylation in h-CaD in porcine carotid arterial muscle strips was at Ser(789); however, the amount of phosphate did not vary appreciably with either KCl or phorbol ester stimulation. Phosphorylation at Ser(759) of h-CaD was almost undetectable (<0.005 mol of phosphate/mol of protein). Moreover, phosphorylation of the low molecular mass isoform of the protein (l-CaD) at the site analogous to Ser(789) was greater in serum-stimulated cultured smooth muscle cells than in serum-starved cells. Serum-stimulated l-CaD phosphorylation was attenuated by the protein kinase inhibitor PD98059. These data 1) identify Ser(789) of h-CaD as the major site of ERK-dependent phosphorylation in carotid arteries; 2) show that the level of phosphorylation at Ser(789) is relatively constant following carotid arterial muscle stimulation, despite an increase in total protein phosphate content; and 3) suggest a functional role for ERK-dependent l-CaD phosphorylation in cell division.

[Rapid inhibitory effect of glucocorticoids on ACh-induced current in rat phaeochromocytoma cells]

A rapid effect of glucocorticoids (GC) on acetycholine-induced current in rat phaeochromocytoma (PC12) cells and its possible mechanism were investigated by whole-cell clamp technique. The results are as follows: The acetylcholine-induced current (IACh) of PC12 cells was proved to be generated through nicotinic ACh receptor by pharmacological identification. ACh (30 mumol/L) induced an inward current at a holding potential (Vh) of -80 mV. The inhibitory effect of corticosterone (B) on IACh was weak when 10(-5) mol/L B and ACh were simultaneously applied extracellularly. Pretreatment of PC12 cells with B could augment the inhibitory effect on peak IACh, and this dose-dependent effect was reversible. At the same concentration of GC, the rank of the inhibitory potency was B > dexamethasone (Dex) > hydrocortisone (F). Extracellular application of B-BSA could also inhibit IACh rapidly. Taken together, it is suggested that GC induced rapid inhibitory effects on IACh in PC12 cells are probably mediated by a nongenomic mechanism. The inhibitory effect of various GC on IACh are different.

Calponin and mitogen-activated protein kinase signaling in differentiated vascular smooth muscle

Contraction of smooth muscle cells is generally assumed to require Ca2+/calmodulin-dependent phosphorylation of the 20-kDa myosin light chains. However, we report here that in the absence of extracellular calcium, phenylephrine induces a contraction of freshly isolated ferret aorta cells in the absence of increases in intracellular ionized calcium or light chain phosphorylation levels but in the presence of activation of mitogen-activated protein kinase. A protein at 36 kDa co-immunoprecipitated with the mitogen-activated protein kinase and was identified as the actin-binding protein, calponin, by immunoblot. An overlay assay further confirmed an interaction between the kinase and calponin, even though the kinase did not phosphorylate calponin in vitro. Calponin also co-immunoprecipitated from smooth muscle cells with protein kinase C-epsilon. High resolution digital confocal studies indicated that calponin redistributes to the cell membrane during phenylephrine stimulation at a time when mitogen-activated protein kinase and protein kinase C-epsilon are targeted to the plasmalemma. These results suggest a role for calponin as a signaling molecule, possibly an adapter protein, linking the targeting of mitogen-activated protein kinase and protein kinase C-epsilon to the surface membrane.

Heat treatment could affect the biochemical properties of caldesmon

Smooth muscle caldesmon (CaD) exhibits apparent heat stability. A widely used purification procedure of CaD involves extensive heat treatment (Bretscher, A. (1984) J. Biol. Chem. 259, 12873-12880). CaD thus purified co-sediments with actin, inhibits actomyosin ATPase activity, and interacts with Ca2+/calmodulin, similarly to the unheated protein. On the other hand, heat-treated CaD binds to actin filaments in a tether-like fashion, whereas lengthwise binding dominates in vivo (Mabuchi, K., Lin, J. J.-C., and Wang, C.-L. A. (1993) J. Muscle Res. Cell Motil. 14, 54-64), suggesting that differences do exist between heat-purified CaD and the native protein. We have isolated, without heat treatment, full-length recombinant chicken gizzard CaD overexpressed in insect cells (High-FiveTM) using a baculovirus expression system. We found that such unheated CaD interacts with calmodulin 10 times stronger than does the heated CaD; its inhibitory action on actomyosin ATPase is reversed by a much lesser amount of calmodulin. Moreover, electron microscopic examination indicated that actin binding at the N-terminal region is more frequent in the unheated CaD, resulting in more lengthwise binding. These findings point to the fact that CaD is not entirely heat-stable; the C-terminal CaM-binding regions and the N-terminal actin-binding region are possibly affected by heat treatment.

[Bovine serum albumin-conjugated corticosterone inhibits the release of arginine vasopressin]

The arginine vasopressin (AVP) released from rat hypothalamic slices containing paraventricular and supraoptic nuclei sectioned with vibratome and incubated in microchambers was measured by radioimmunoassay. The effect of bovine serum albumin-conjugated corticosterone (B-BSA) on the AVP release was investigated. The results were as follows: (1) B-BSA, within 20 min, inhibited the AVP release in a dose-dependent manner from 10(-7) to 10(-4) mol/L. (2) The inhibitory effect of B-BSA was partially blocked by RU486 (10(-4)-10(-3) mol/L). (3) With the elevation of Ca2+ in the incubation medium the inhibitory effect of B-BSA was enhanced. (4) The inhibitory effect of B-BSA was also enhanced in the presence of neomycin (10(-3)-10(-2) mol/L). These results suggested that glucocorticoid, without entering into cells, could inhibit AVP release from rat hypothalamic slices. This effect might be mediated via a non-genomic mechanism involving a change of Ca2+ influx across the cell membrane.

Nongenomic effect of glucocorticoid on the release of arginine vasopressin from hypothalamic slices in rats

The arginine vasopressin (AVP) released from the hypothalamic slices containing paraventricular and supraoptic nuclei of Sprague-Dawley rats sectioned with vibratome and incubated in static microchambers was measured by radioimmunoassay, and the rapid effect and its underlying mechanism of glucocorticoids (GC) on AVP release were investigated. The results were as follows: (1) AVP was steadily released at a rate of 9.1 +/- 1.2 pg/min/well for as long as 6 h. (2) Corticosterone (B), within 20 min, inhibited AVP release in a dose-dependent manner from 10(-7) to 10(-4) mol/l. (3) Cortisol, 17beta-estradiol, or testosterone (all in 10(-6) mol/l) to some extent also inhibited AVP release, but dexamethasone, aldosterone, progesterone, RU 38486 or cholesterol had no significant inhibition on AVP release. (4) The rapid inhibitory effect of B was not affected by actinomycin D, puromycin or colchicine. (5) RU 38486 (10(-5)-10(-3) mol/l) could partially block the rapid inhibitory effect of B, although it did not by itself change AVP release. (6) With the elevation of Ca2+ in the incubation medium, the AVP release was increased and the rapid inhibitory effect of B enhanced; while in the absence of Ca2+ the AVP release decreased and the effect of B attenuated. (7) The rapid inhibitory effect of B was enhanced in the presence of neomycin, although the latter had no influence on AVP release. (8) Aminophylline did not affect the rapid inhibitory effect of B. These results indicated that the rapid inhibitory effect of GC might be a nongenomic rather than the classical genomic one, and that the extracellular Ca2+ play a role in the rapid effect of GC on AVP release. The significance of the rapid action of GC in the rapid negative feedback regulation of AVP release from hypothalamus of rats was discussed.

[Effect of glucocorticoids and other steroids on arginine vasopressin release from rat hypothalamic slices]

Rat hypothalamic slices sectioned with vibratome (containing paraventricular and supraoptic nuclei) were incubated in static microchamber and the Arginine vasopressin (AVP) released from the slices was measured by radioimmunoassay. The effect of glucocorticoids (GC) and other steroids on AVP release was investigated. The results were as follows: (1) AVP was steadily released at a rate of 9.06 +/- 1.23 pg/min for as long as 6 h (not including the 90 min for recovery of slices). (2) Corticosterone (B) inhibited AVP release within 20 min in a dose-dependent manner from 10(-7) to 10(-4) mol/L. (3) Cortisol, 17 beta-estradiol, or testosterone (10(-6) mol/L) also inhibited AVP release within 20 min, but dexamethasone, aldosterone, progesterone, RU486, or cholesterol had no significant effect. (4) RU486 (10(-5)-10(-3) mol/L) could partially block the rapid inhibitory effect of corticosterone. These results suggested that GC might exert in situ a regulatory negative feedback action on the AVP release from hypothalamus of rat through a non-genomic rather than a genomic mechanism.

Heterodyne nondegenerate pump-probe measurement technique for guided-wave devices

We describe a new heterodyne nondegenerate pump-probe waveguide measurement technique that permits independent control of wavelengths, pulse widths, and polarizations of the pump and probe pulses in a collinear geometry. This technique provides both time- and spectral-domain information and can be applied to transmission and index measurements alike. We demonstrate this technique for the measurement of gain dynamics in a strained-layer single-quantum-well diode laser.

[Evaluation of radiation doses in mammography]

A dedicated X-ray mammography was introduced to our hospital from 1987 and an imaging receptor of xeroradiography was applied. We reported previously that the average air exposure was 0.79R and that the absorption dose of skin was 1.00 rad. These data are similar to literature reports. Screen-film mammography was introduced recently. To select the best breast imaging and the least radiation exposure, diverse methods were investigated. A dosimetry (Capintec model 192) and a PS-033 parallel ionization chamber were applied to compare the absorption dose on polystyrene phantom between various exposure factors, the application of breast clamp and the size of exposure field. Retrospective estimation of the radiation dose was obtained from the exposure factors of previous mammography since July, 1990 to May, 1992. There were 1035 xeromammographic examinations and 358 examinations with medium-speed screen-film mammography. Another 61 craniocaudal and 96 mediolateral projections with high-speed screen-film mammography were recruited during the recent two months. An ionization chamber (Exradin, Shonka-Wyckoff A5) with an electrometer (Keithley 617) wer selected to obtain the dose equivalent from air exposure between selected exposure factors. The radiation dose of mammography is linearly correlated with voltage/kV and current/mAs. The application of a breast clump reduces 10% of the skin dose. The average exposure factors of xeromammography are 45.6 kV, 163.5 mAs. These results remain the same as in our previous report. Xeromammography has a greater exposure to air, estimated average glandular dose and absorbed dose than screen-film mammography. The mean exposure factor of rapid screen-film mammography gains half the value of medium screen-film mammography, ie. 26.6 kV, 87.0 mAs vs. 26.0 kV, 164.5 mAs.(ABSTRACT TRUNCATED AT 250 WORDS)

Room-temperature diode-pumped Yb:YAG laser

We have developed an efficient room-temperature ytterbium-doped YAG laser operating at 1.03 microm pumped by an InGaAs strained-layer diode laser operating at 968 nm. The threshold was 234 mW and 23 mW of output power was obtained for an absorbed pump power of 345 mW. This laser offers a number of advantages over AlGaAs pumped Nd:YAG lasers, such as broader absorption features, longer fluorescent lifetime, and lower thermal loading of the gain medium.

[The rapid effect of the iontophoretically applied cortisol on unit activity of neurons in three brain areas in rats]

The present study was undertaken to analyze whether the glucocorticoid (GC) effect was region specific in the brain. Na-cortisol-succinate (HC) was applied iontophoretically to cerebral cortex (CX), hippocampus (HPC) and PVN respectively and the effect on unit discharge rate in these three brain areas were compared. In cerebral cortex, the percentage of responsive neurons was only 8% (4/50), which was significantly lower than those in HPC (10/36, 27.8%) and PVN (9/35, 25.7%). The difference in the occurrence is paralleled with the known distribution of traditional GC cytosolic receptors in the brain. In all the three brain areas studied the main response to GC was inhibitory and the latencies of the responses were 9.6 +/- 6.5, 22.7 +/- 24.0, and 14.5 +/- 11.5 s and the durations of the after-effect were 74.8 +/- 66.5 (n = 4), 24.2 +/- 14.5 (n = 6) and 21.0 +/- 10.5 s (n = 9) respectively. The shortness of the latencies once again suggests that the mechanism involved is non-genomic. It is interest to note that in some HPC neurons the after-effect lasted for 1758 +/- 2148 s (n = 4). The results show that the rapid effect of GC on neurons is different in the three brain areas studied in regarding to the occurrence of responsive neurons and the duration of the after-effects.

An electrophysiological study on the membrane receptor-mediated action of glucocorticoids in mammalian neurons

The action of glucocorticoids (GC) on neuronal cell membrane was studied in isolated and superfused guinea pig coeliac ganglia by the intracellular recording technique. Cortisol succinate (F) hyperpolarized the membrane potential of 47 of 179 cells and changed the cell's input resistance with a latency of less than 2 min in vitro. The effect persisted under low Ca2+/high Mg2+ superfusing condition and could be blocked by RU 38486, a competitive antagonist of GC cytosolic receptor. Cortisol-21-bovine albumin conjugant exhibited the same effect. Corticosterone (B) elicited hyperpolarization in another 15 of 83 cells, but dexamethasone (Dex) did not. Dex, however, depolarized 2 of 18 cells. Aldosterone, cholesterol and vehicle (ethyl alcohol) caused no detectable change in membrane potential. In vivo studies by iontophoretic application of steroids to hypothalamic paraventricular (PVN) neurons showed that F inhibited the unit discharges in 68 of 97 PVN neurons, and the effect could be antagonized by RU 38486. Dex excited 30 of 100 neurons. Estradiol (E) also inhibited the discharges, but this inhibition was not antagonized by RU 38486. The effect of GC on PVN neurons was also examined in hypothalamic slices including the paraventricular nucleus. B inhibited 28 of 104 units and excited 7 of 104 cells, and both effects could be antagonized by RU 38486. The threshold of inhibitory response was about 10(-7) M, which is close to the physiological level of the hormone in plasma. The results suggest that GC can act non-genomically and specifically through its membrane receptor on the neuronal surface, and that there might be a chemical similarity between the membrane receptor and the traditional cytosolic GC receptor.(ABSTRACT TRUNCATED AT 250 WORDS)

[Responses of midbrain central gray neurons activated by hypothalamic paraventricular nucleus (PVH) stimulation to somatic afferent input in rats]

Extracellular single unit recordings were made from 318 neurons within the midbrain central gray in urethane-anesthetized rats. Following electrical stimulation of the hypothalamic paraventricular nucleus (PVH), 10% of the units in central gray (CG) were antidromically activated, while 7.5% were orthodromically excited, and 0.7% were orthodromically inhibited. Among these antidromically activated neurons, 28 units were further examined for their responsiveness to peripheral somatic sensory stimulation. Strong electrical stimulation of contralateral sciatic and tibial nerve, and tail pinching produced excitation in 12 and inhibition in 2 units. No significant responses to non-noxious stimulation were observed in these units. Of the 26 orthodromically activated units, 14 were excited and 4 inhibited by the sciatic nerve stimulation or tail pinching. These results support the hypothesis that CG is one of the relay stations in the afferent pathway of somatic sensory especially, noxious, information transmitting to the PVH, and that the PVH may play a role in central pain control or modulation via their descending influence on CG unit.

Functioning oxyphil cell adenomas of the parathyroid gland. A study of 15 cases

Parathyroid adenomas composed predominantly of chief cells are the most frequent cause of primary hyperparathyroidism. Until as recently as 1978, the rare oxyphil cell parathyroid adenoma was generally considered nonfunctioning. A retrospective review of 500 consecutive patients at the Massachusetts General Hospital with a diagnosis of hyperparathyroidism associated with parathyroid adenoma during the years 1979-1987 yielded 15 (3.0%) oxyphil cell adenomas. A total of 65 case reports of hyperparathyroidism associated with a diagnosis of oxyphil cell adenomas were reviewed, applying the same diagnostic criteria used in case selection for the present series. These criteria include: (a) at least 90% composition of the adenoma by oxyphil cells; (b) biopsy or excision of a second histologically normal parathyroid gland to help rule out hyperplasia; and (c) postoperative alleviation of hypercalcemia. More than 50% of the previously reported cases did not conform to these criteria. The findings in the present study further document the entity of hyperparathyroidism caused by oxyphil cell parathyroid adenomas and suggest criteria guidelines for this rare diagnosis.

Rapid diagnosis of adult diarrhea rotavirus (ADRV): detection of viral antigens in faecal samples using staphylococcal co-agglutination test

Staphylococcus aureus Cowan I rich in protein A when sensitized with guinea pig antiserum to adult diarrhea rotavirus (ADRV) at 1:16 gave a strong co-agglutination with ADRV-positive faecal samples as previously confirmed by electron microscopy (EM) and enzyme-linked immunosorbent assay (ELISA). The bacteria sensitized with normal guinea pig serum did not give any co-agglutination. Blocking tests using rabbit ADRV-specific antiserum for the treatment of twelve ADRV-positive samples abolished the reaction. All the fifty ELISA-confirmed ADRV-positive faecal samples gave positive co-agglutination, whereas all the forty-eight ELISA-negative faecal samples from healthy subjects gave negative results. The test has been proved to be rapid, simple, specific, and economic, useful for rapid diagnosis even in remote areas, so that the ADRV infection can definitely be differentiated from some of acute bacterial diarrheas.

Multiple branchial cleft-like cysts in Hashimoto's thyroiditis

We report two cases of multiple intrathyroidal cysts in women with Hashimoto's thyroiditis. The cysts were lined by squamous and focally columnar epithelium, and they were surrounded by follicular lymphoid tissue and a fibrous capsule. They appeared similar to branchial cleft cysts of the lateral neck and were distinct from previously reported types of thyroid cysts. Although the histogenesis of these lesions is unclear, they are probably derived from developmental rests. A relationship between the cystic enlargement of these rests and the Hashimoto's disease seems likely.

Intraoperative measurement of parathyroid hormone in the surgical management of hyperparathyroidism

The operative management of patients with hyperparathyroidism is controversial. Higher rates for persistent hypercalcemia and postoperative hypoparathyroidism are seen in multiple-gland hyperplasia and in bilateral neck exploration. Hyperparathyroid patients undergoing unilateral neck exploration with removal of a single parathyroid adenoma have a rapid clearance of parathyroid hormone (PTH) that declines to undetectable levels within hours after successful parathyroid surgery. We have taken advantage of a sensitive immunoradiometric assay (IRMA) for the secreted biologically active, intact PTH-(1-84) molecule and demonstrated a decline of PTH to less than 40% of baseline values 15 minutes after successful parathyroid adenomectomy in 12 patients. Intraoperative measurement of PTH by modification of this IRMA may complement surgical skill and histopathologic information and has the potential for providing guidance regarding the extent of neck exploration necessary for determining surgical care of hyperparathyroidism.

Recovery of parathyroid hormone secretion after parathyroid adenomectomy

Using a sensitive two-site immunoradiometric assay which detects only intact human PTH-(1-84), we studied the kinetics of PTH secretion in 19 patients undergoing unilateral neck exploration and removal of a parathyroid adenoma. Preoperative serum PTH values averaged 116 ng/L (normal, 12-65 ng/L). In 8 patients in whom intraoperative sampling was performed, clearance of PTH-(1-84) was rapid, with virtual disappearance of PTH by 120 min after clamping the vascular pedicle to the adenoma. Analysis of the rate of disappearance of PTH-(1-84) indicated an exponential decay with a half-life of 21 min. Thirteen of 19 patients had serum PTH values less than 1 ng/L within 8 h after parathyroidectomy. Recovery of PTH secretion from the suppressed nonsurgically manipulated parathyroid tissue occurred during the nadir of postoperative hypocalcemia. Serum PTH was greater than 10 ng/L in 16 of 19 patients 30 h after removal of the PTH adenoma. Therefore, the functional recovery of atrophic parathyroid tissue is more rapid than that of other endocrine tissues studied to date.

Treatment of intrathyroidal papillary carcinoma of the thyroid

Among 237 patients with grossly noninvasive (intrathyroidal) papillary carcinoma of the thyroid treated by surgery at the Massachusetts General Hospital and followed for a median of 14 years, no patient had tumor recurrence either in the thyroid bed or opposite lobe. There were 12 metastatic recurrences with risks of recurrence 4.0% and 6.9% at 10 years and 20 years respectively. Eight of these recurrences were restricted to cervical lymph nodes and did not herald the development of more serious recurrent disease. The remaining recurrences were lung metastases in four patients, two of whom died, accounting for the only deaths from thyroid carcinoma in this series. Factors that influenced the risk of recurrence included lymph node metastases at initial surgery, large tumor size, and to a lesser extent, male sex. The majority of patients (176) had subtotal thyroidectomies, mostly lobectomy (131 patients). There was no evidence that the 61 patients who underwent total thyroidectomy fared better than those with similar patient and tumor characteristics on whom subtotal procedures were performed. The overall findings of this study strongly support the concept that intrathyroidal thyroid carcinoma can be successfully treated by conservative surgery.

The management of 50 unusual hyperfunctioning parathyroid glands

From 1926 to 1984, 1200 patients with hyperparathyroidism were treated surgically at Massachusetts General Hospital (MGH). This series included 50 (4%) unusual cases that involved anomalous parathyroid locations or supernumerary hyperfunctioning parathyroid glands. In 42 cases the diseased glands were found in unusual locations: In three patients, glands were high in the neck behind the angle of the jaw; nine patients' glands were entirely encapsulated within the thyroid gland; and 30 patients required sternotomy for removal of mediastinal tumors. The eight remaining patients (as well as five of the mediastinal cases) had supernumerary hyperfunctioning glands. The three undescended parapharyngeal neoplasms, five of the cervical supernumerary tumors, and the majority of the mediastinal glands were associated with the thymus gland or thymic remnants. These glands appeared to arise from undescended parapharyngeal vestiges, partially descended parathymus remnants deposited along the path of developmental migration, or hyperdescended mediastinal inferior glands from branchial pouch III. The nine intrathyroid parathyroids were totally enclosed within the thyroid parenchyma. These appeared to arise from superior parathyroid glands that were trapped during fusion of the lateral wing portion from branchial pouch IV with the developing lateral lobes of the median thyroid primordium. Of these fifty cases, 39 patients had undergone a total of 60 previous operations (57 cervical and three mediastinal explorations) at MGH (16 patients) or other institutions (23 patients). In eleven patients the unusual hyperfunctioning gland was successfully identified at the time of the initial operation. Forty-four patients (88%) were surgically cured, as evidenced by eucalcemia. There were six patients with permanent hypoparathyroidism and none with persistent or recurrent hyperparathyroidism.

Highly sensitive two-site immunoradiometric assay of parathyrin, and its clinical utility in evaluating patients with hypercalcemia

We have developed a highly sensitive, two-site immunoradiometric assay (IRMA) for human parathyrin (PTH) that is specific for the intact, secreted, biologically active 84-amino-acid peptide. This assay has several technical advantages: it does not detect even high concentrations of inactive carboxyl-terminal fragments, results are available within 24 h, and the detection limit for intact hormone is low (1 ng/L). The assay readily measures concentrations of PTH in all healthy subjects and distinguishes these values from low or undetectable PTH values observed in clinical situations in which PTH secretion is expected to be suppressed. We found complete separation of results from 37 patients with surgically proven hyperparathyroidism and those from 23 patients with hypercalcemia associated with malignancy, the latter having PTH values at or below the lower limits of normal for this assay. The sensitivity, specificity, and rapid turnaround time of this two-site IRMA should advance the laboratory evaluation of patients with disorders of calcium metabolism.

Highly sensitive two-site immunoradiometric assay of parathyrin, and its clinical utility in evaluating patients with hypercalcemia

We have developed a highly sensitive, two-site immunoradiometric assay (IRMA) for human parathyrin (PTH) that is specific for the intact, secreted, biologically active 84-amino-acid peptide. This assay has several technical advantages: it does not detect even high concentrations of inactive carboxyl-terminal fragments, results are available within 24 h, and the detection limit for intact hormone is low (1 ng/L). The assay readily measures concentrations of PTH in all healthy subjects and distinguishes these values from low or undetectable PTH values observed in clinical situations in which PTH secretion is expected to be suppressed. We found complete separation of results from 37 patients with surgically proven hyperparathyroidism and those from 23 patients with hypercalcemia associated with malignancy, the latter having PTH values at or below the lower limits of normal for this assay. The sensitivity, specificity, and rapid turnaround time of this two-site IRMA should advance the laboratory evaluation of patients with disorders of calcium metabolism.

Sonography in the follow-up of 100 patients with thyroid carcinoma

High-frequency, high-resolution sonography was used to detect recurrent thyroid carcinoma in 73 patients with papillary carcinoma, 16 with medullary carcinoma, 10 with follicular carcinoma, and one with small-cell carcinoma. Of the 36 patients with negative sonograms, 35 had no other evidence of recurrence, while one had surgical proof of recurrence. Of 25 patients with positive sonograms, confirmed with surgery or radioactive iodine (I131) scanning (sonographic sensitivity 96%, specificity 83%), palpation was negative in 17 (palpation sensitivity 32%, specificity 100%). Thirty-two patient with positive sonographic findings had no objective clinical proof of recurrence. There were seven false-positive studies. This study suggests that sonography may be the method of choice for earliest detection and localization of recurrent carcinoma of the thyroid.

Encapsulated follicular carcinoma of the thyroid: diagnosis, treatment, and results

Nineteen cases of encapsulated follicular carcinoma of the thyroid treated at the Massachusetts General Hospital from 1962 to 1979 are reviewed. In all patients the encapsulated nodules had histologic evidence of capsular or vascular invasion. There were 13 women and six men with ages ranging from 14 to 74 years. Eight of the 19 patients underwent large-needle thyroid biopsies before surgery, and in each patient a hypercellular lesion was identified requiring surgery to exclude malignancy. The operative approach was ipsilateral lobectomy with removal of sufficient thyroid tissue to assure that resection margins were free of disease. The size of the tumors ranged from 2 to 6.5 cm in greatest diameter. The mean follow-up was 112 months. Three patients developed ipsilateral neck recurrences. Four patients developed metastases to the bone, brain, or lung. The time from initial operation to recurrence or metastasis ranged from 0 to 241 months (mean, 69 months). There was a 5-year survival rate of 88% and a 10-year survival rate of 78%. Only two of the six patients with complete follow-up died of thyroid malignancy. Of the 16 patients with recurrent or metastatic disease, two died of the disease. No patient whose lesion was 3 cm or smaller developed metastases or recurrences, and of the 10 patients with lesions 3.5 cm or larger, six developed metastatic or recurrent disease. Age was also a prognostic factor, since four of the six patients over 60 years old developed recurrent or metastatic disease.

Malignant lymphoma of the thyroid gland: a clinical and pathologic study of twenty cases

Among 20 patients with malignant lymphoma of the thyroid gland, the mean age at diagnosis was 63 years and the male to female ratio was 1:6. All patients had a firm, rapidly enlarging neck mass. In 90% of the patients the mass had been present for less than 1 year; in 40%, for less than 1 month. Approximately half of the patients tested had hypothyroidism; three fourths had elevated antithyroid antibodies. There was one nodular lymphoma. The remaining 17 cases available for review were diffuse. Thyroid lobectomy was performed in seven patients, limited excision in eight, and needle biopsy alone in five. External irradiation was administered in 11 cases (55%). Chemotherapy was used alone in one patient (5%) and in combination with radiotherapy in eight (40%). Six patients (30%) were alive without evidence of recurrent disease at follow-up ranging from 1 to 12 years. Eleven patients had died of lymphoma, all but one dying within 1 year. One patient died of other causes and two were lost to follow-up study. There was no appreciable effect of patient age or sex, lymphoma histology, or extent of surgical resection on survival. Treatment of choice for primary lymphoma of the thyroid gland appears to be external irradiation or chemotherapy, alone or in combination. The role of surgery is limited to making a tissue diagnosis of lymphoma, unless the tumor is completely intrathyroidal.