Multidrug-resistance in methicillin-resistant Staphylococcus aureus (MRSA) isolated from a subtropical river contaminated by nearby livestock industries

Methicillin-resistant Staphylococcus aureus (MRSA) is a major threat to public health that causes infections in hospitals, communities, and animal husbandry. Livestock-associated MRSA (LA-MRSA) is defined as MRSA possessing staphylococcal cassette chromosome mec (SCCmec) IV or V, both of which lacks the Panton-Valentine leukocidin (PVL) gene but has variable combinations of antimicrobial susceptibility. This study focused on Taiwan's subtropical river basin and the Puzih River, which converges from tributaries flowing through downtown and animal husbandry areas. MRSA was detected at a rate of 7.8% in the tributaries, which was higher than downstream (2.1%). The ratio of multidrug-resistant (MDR) MRSA (n = 30) to total MRSA isolates (n = 39) was 0.769, and most of the MDR MRSA isolates (66.7%, 20/30) exhibited resistance to chloramphenicol, ciprofloxacin, clindamycin, erythromycin, sulfamethoxazole-trimethoprim, and tetracycline. The number of MDR MRSA isolates in the tributaries was also higher than the downstream regions of the Puzih River. The majority of MRSA isolates (64.1%) observed in this study possessed SCCmec type IV without PVL, which is typical for LA-MRSA. Enterobacterial repetitive intergenic consensus PCR (ERIC-PCR) typing aided the discrimination of resistance patterns among SCCmec types. This study highlights the threat to human health posed by the waterborne transmission of MDR LA-MRSA.

High-power structured laser modes: manifestation of quantum Green's function

The distributions of resonant frequencies in an astigmatic cavity are theoretically confirmed to be analogously equivalent to the quantum energy structures of two-dimensional commensurate harmonic oscillators. In the first part [Opt. Lett.45, 4096 (2020)OPLEDP0146-959210.1364/OL.399251] of this two-part series study, the lasing modes were verified to reveal a variety of vortex array structures. Here, in the second part of this two-part series study, the lasing modes are confirmed to agree very well with the quantum Green's functions that correspond to a bundle of Lissajous figures in the high-order regime.

High-power structured laser modes: direct generation of a vortex array

The frequency degeneracy induced by the astigmatism in a nearly hemispherical cavity is originally exploited to generate vortex array laser modes with the output power up to 300 mW. The inhomogeneous Helmholtz equation is employed to derive the wave function for manifesting the characteristics of the lasing modes. The theoretical wave function explicitly reveals the role of the Gouy phase in the formation of vortex arrays. Numerical analyses are further performed to confirm that the thermal lensing effect in the laser crystal assists the lasing transverse order to increase with increasing pump power. It is believed that the high efficiency enables the present laser modes to be useful in the applications of structured vortex beams.

Control of metamorphic buffer structure and device performance of In(x)Ga(1-x)As epitaxial layers fabricated by metal organic chemical vapor deposition

Using a step-graded (SG) buffer structure via metal-organic chemical vapor deposition, we demonstrate a high suitability of In0.5Ga0.5As epitaxial layers on a GaAs substrate for electronic device application. Taking advantage of the technique's precise control, we were able to increase the number of SG layers to achieve a fairly low dislocation density (∼10(6) cm(-2)), while keeping each individual SG layer slightly exceeding the critical thickness (∼80 nm) for strain relaxation. This met the demanded but contradictory requirements, and even offered excellent scalability by lowering the whole buffer structure down to 2.3 μm. This scalability overwhelmingly excels the forefront studies. The effects of the SG misfit strain on the crystal quality and surface morphology of In0.5Ga0.5As epitaxial layers were carefully investigated, and were correlated to threading dislocation (TD) blocking mechanisms. From microstructural analyses, TDs can be blocked effectively through self-annihilation reactions, or hindered randomly by misfit dislocation mechanisms. Growth conditions for avoiding phase separation were also explored and identified. The buffer-improved, high-quality In0.5Ga0.5As epitaxial layers enabled a high-performance, metal-oxide-semiconductor capacitor on a GaAs substrate. The devices displayed remarkable capacitance-voltage responses with small frequency dispersion. A promising interface trap density of 3 × 10(12) eV(-1) cm(-2) in a conductance test was also obtained. These electrical performances are competitive to those using lattice-coherent but pricey InGaAs/InP systems.

Prevalence and genotype of Giardia duodenalis from faecal samples of stray dogs in Hualien city of eastern Taiwan

Giardia duodenalis is a zoonotic protozoan parasite that causes diarrhea through waterborne transmission or fecal-oral infection. The cysts are chlorine-resistant and, therefore, can pollute drinking water and induce a pandemic disease. In this study, we aimed to detect G. duodenalis infection in stray dogs in Hualien, Taiwan. We collected faecal samples from 118 dogs and amplified DNA sequences of the β-giardin gene by nested polymerase chain reactions (nested PCR). Eleven of the 118 faecal samples tested positive for the parasite. The genotype analysis of the 11 samples indicated that 7 samples belonged to assemblage C and four samples belonged to assemblage D. Our study provided a better understanding of the infection rate and genotypes of G. duodenalis in dogs from Hualien City, and human infection could not be induced by this zoonotic infection pathway in Hualien City.

Endothelial Progenitor Cells Derived From Wharton's Jelly of Human Umbilical Cord Attenuate Ischemic Acute Kidney Injury by Increasing Vascularization and Decreasing Apoptosis, Inflammation, and Fibrosis

Ischemia-reperfusion (I/R) injury to the kidney, a major cause of acute renal failure in humans, is associated with a high mortality, and the development of a new therapeutic strategy is therefore highly desirable. In this study, we examined the therapeutic potential of implantation of endothelial progenitor cells (EPCs) isolated from Wharton's jelly of human umbilical cords in the treatment of renal I/R injury in mice. To visualize the localization of the transplanted EPCs, the cells were labeled with Q-tracker before injection into the renal capsule. Mice with renal I/R injury showed a significant increase in blood urea nitrogen and creatinine levels, and these effects were decreased by EPC transplantation. The kidney injury score in the mice with I/R injury was also significantly decreased by EPC transplantation. EPC transplantation increased the microvascular density, and some of the EPCs surrounded and were incorporated into microvessels. In addition, EPC transplantation inhibited the I/R-induced cell apoptosis of endothelial, glomerular, and renal tubular cells, as demonstrated by TUNEL staining, and significantly reduced reactive oxygen species production and the expression of the inflammatory chemokines macrophage inflammatory protein-2 and keratinocyte-derived cytokine, as shown by immunostaining and ELISA. Moreover, EPC transplantation reduced I/R-induced fibrosis, as demonstrated by immunostaining for S100A4, a fibroblast marker, and by Jones silver staining. To our knowledge, this is the first report that transplantation of EPCs from Wharton's jelly of human umbilical cords might provide a novel therapy for ischemic acute kidney injury by promoting angiogenesis and inhibiting apoptosis, inflammation, and fibrosis.

Instrument for x-ray magnetic circular dichroism measurements at high pressures

An instrument has been developed for x-ray magnetic circular dichroism (XMCD) measurements at high pressures and low temperatures. This instrument couples a nonmagnetic copper-beryllium diamond anvil cell featuring perforated diamonds with a helium flow cryostat and an electromagnet. The applied pressure can be controlled in situ using a gas membrane and calibrated using Cu K-edge x-ray absorption fine structure measurements. The performance of this instrument was tested by measuring the XMCD spectra of the Gd(5)Si(2)Ge(2) giant magnetocaloric material.

Primary intracranial myxopapillary ependymomas: report of two cases and review of the literature

Myxopapillary ependymoma is a variant of ependymoma occurring almost exclusively in the conus medullaris or filum terminale. Myxopapillary ependymoma found primarily in the brain is extremely rare. Two such cases appearing at the 4th ventricle and cerebral falx are reported. The imaging features of such tumors are a primary cystic mass with strong enhancement at its solid part. Myxopapillary ependymoma should be a possible differential diagnosis when an intracranial cystic tumor is found.

Spectrofluorometric analysis of length-dependent conformational changes in cardiac troponin C

Length modulation of cardiac muscle is manifested in the Frank-Starling relation of the heart. Recently, it has been shown that length-dependent changes in SH reactivity of cardiac troponin C (cTnC) occurred in association with cross-bridge attachment and Ca2+. However, the presence of two SH groups (Cys-35 and Cys-84) in the regulatory region of cTnC complicates efforts to detect conformational changes. In this study skinned porcine cardiac fibers were reacted with 7-diethylamino-3-[4'maleimidylphenyl]-4-methylcoumarin (CPM). Alkaline urea gel electrophoresis, along with protein elution, was used to isolate filament bound cTnC. Analysis of fluorescence measurement showed that there is a Ca(2+)-increased fluorescence for CPM-labeled cTnC in long fibers (sarcomere length = 2.2 approximately 2.5 microm) but not in short fibers (sarcomere length = 1.6 approximately 1.8 microm). In addition, the labeled cTnC was measured for the fluorescence decrease over time by adding a non-fluorescence energy acceptor, 4-dimethylaminophenylazophenyl-4'maleimide (DABMI), in the presence and absence of Ca2+. Fluorescence quenching by DABMI is not affected by Ca2+ in long fibers but it is significantly increased in short fibers. However, the fibers maintained in the relaxed state with 5 mM MgATP and 1 mM Vanadate showed no length effect on the CPM-labeled cTnC in terms of the Ca(2+)-mediated changes in fluorescence spectrum and in fluorescence quenching by DABMI. All together, our results suggest that the relative reactivities of Cys-35 and Cys-84 vary with sarcomere length.

Characteristics of community-acquired methicillin-resistant Staphylococcus aureus in infants and children without known risk factors

This retrospective study sought to determine the characteristics of community-acquired methicillin-resistant Staphylococcus aureus (CA-MRSA) infections in patients younger than 18 years without known risk factors who were treated at a teaching hospital in central Taiwan. Epidemiological and clinical data were collected from medical charts. Possible risk factors included hospitalization within the past 6 months, transfer from other hospitals or nursing homes, and having underlying illness. A total of 173 isolates of community-acquired S. aureus were analyzed. Seventeen (9.8%) of these 173 isolates were methicillin-resistant S. aureus collected from patients without risk factors, 31 (17.9%) were methicillin-resistant S. aureus from patients with risk factors, and the other 125 (72.3%) were methicillin-susceptible S. aureus. Most isolates of community-acquired methicillin-resistant S. aureus collected from patients without risk factors (14/17, 82.4%) were obtained from the infected wounds of skin or soft tissues. Only 4 (23.5%) in 17 patients with isolates resistant to methicillin were prescribed antimicrobial therapy with glycopeptides. Nevertheless, all patients recovered without any long-term sequelae. These results highlight the fact that community-acquired methicillin-resistant S. aureus infections occur frequently in Taiwan among patients who have no established risk factors for this infection.

Mandibular second molar periodontal status after third molar extraction

BACKGROUND

Extraction and treatment of third molars have been cited as causing periodontal problems. To evaluate the long-term effects of third molar extraction on the periodontal health of the mandibular second molar, a comparison of the periodontal status was performed around 2 groups of mandibular second molars, with and without third molar extraction.

METHODS

A total of 312 sites in 57 adult periodontitis patients were examined and the buccal and lingual locations of the mesial and distal root surfaces around the second molars were recorded. Two-hundred and thirty-two sites were experimental teeth; i.e., third molars had been surgically removed more than 5 years ago, 80 sites served as control molars; i.e., congenitally missing third molars. Clinical periodontal parameters including probing depth, attachment loss, and gingival recession and radiographic intrabony level were measured. The effects of the surgery and the examination (buccal or lingual) locations on the measurements were statistically analyzed.

RESULTS

Neither extraction history nor examination location affected the probing depth on mesial surfaces. However, significant effects of the surgical history on the probing depth were observed on the distal surfaces. Similar results of greater attachment loss and radiographic alveolar bone loss were observed only at the distal sites of the experimental group. In addition, the increased radiographic bone loss was only found at the distal sites (adjacent to the surgical location) and not at the mesial sites (distant from the surgical location) on the experimental group.

CONCLUSIONS

In this study, greater periodontal breakdown, including probing depth, attachment loss, and radiographic alveolar bone loss, was found at the distal sites, but not at the mesial sites, of the experimental molars where the third molar was surgically extracted compared with the control teeth (no surgery). In the experimental molars, more radiographic bone loss was found at the sites adjacent to the surgical location than at the sites distant to the surgical location. Therefore, we suggest that the surgical removal of the mandibular third molar may lead to a periodontal breakdown on the distal surface of the second molar. Periodontal re-evaluation after the initial healing of third molar extraction is indicated.

Enhanced drug dissolution and bulk properties of solid dispersions granulated with a surface adsorbent

A combination of solid dispersion and surface adsorption techniques was used to enhance the dissolution of a poorly water-soluble drug, BAY 12-9566. In addition to dissolution enhancement, this method allows compression of the granulated dispersion into tablets. Gelucire 50/13 (polyglycolized glycerides) was used as the solid dispersion carrier. Hot-melt granulation was performed to adsorb the melt of the drug and Gelucire 50/13 onto the surface of Neusilin US2 (magnesium alumino silicate), the surface adsorbent. Dispersion granules using various ratios of drug-Gelucire 50/13-Neusilin US2 were thus prepared. The dissolution profiles of BAY 12-9566 from the dispersion granules and corresponding physical mixtures were evaluated using USP Type II apparatus at 75 rpm. The dissolution medium consisted of 0.1 N hydrochloric acid (HCl) with 1% w/v sodium lauryl sulfate (SLS). Dissolution of BAY 12-9566 from the dispersion granules was enhanced compared to the physical mixture. The dissolution of BAY 12-9566 increased as a function of increased Gelucire 50/13 and Neusilin US2 loading and decreased with increased drug loading. In contrast to the usually observed decrease in dissolution on storage, an enhancement in dissolution was observed for the dispersion granules stored at 40 degrees C/75% relative humidity (RH) for 2 and 4 weeks. Additionally, the flow and compressibility properties of dispersion granules were improved significantly when compared to the drug alone or the corresponding physical mixture. The ternary dispersion granules were compressed easily into tablets with up to 30% w/w drug loading. The extent of dissolution of drug from these tablets was greater than that from the uncompressed dispersion granules.

Treatment of tooth fracture by medium-energy CO2 laser and DP-bioactive glass paste: the interaction of enamel and DP-bioactive glass paste during irradiation by CO2 laser

Acute trauma or trauma associated with occlusal disturbance can produce tooth crack or fracture. Although several methods are proposed to treat the defect, however, the prognosis is generally poor. If the fusion of a tooth fracture by laser is possible, it will offer an alternative to extraction or at least serve as an adjunctive treatment in the reconstruction. We have tried to use a continuous-wave CO2 laser and a newly developed DP-bioactive glass paste (DPGP) to fuse or bridge tooth crack or fracture lines. Both the DP-bioactive glass paste and tooth enamel have strong absorption bands at the wavelength of 10.6 microm. Therefore, under CO2 laser, DPGP and enamel should have an effective absorption and melt together. The interface between DPGP and enamel could be regarded as a mixture of DPGP and enamel (DPG-E). The study focused on the phase transformation, microstructure, functional group and thermal behavior of DPG-E with or without CO2 laser irradiation, by the analytical techniques of XRD, FTIR, DTA/TGA, and SEM. The results of XRD showed that the main crystal phase in the DPG-E was dicalcium phosphate dihydrate (CaHPO4.2H2O). It changed into CaHPO4, gamma-Ca2P2O7, beta-Ca2P2O7 and finally alpha-Ca2P2O7 with increasing temperature. In the FTIR analysis, the 720 cm(-1) absorption band ascribed to the P-O-P linkage in pyrophosphate rose up and the intensities of the OH- bands reduced after laser irradiation. In regard to the results of DTA/TGA after irradiation, the weight loss decreased due to the removal of part of absorption water and crystallization water by the CO2 laser. SEM micrographs revealed that the melted masses and the plate-like crystals formed a tight chemical bond between the enamel and DPGP. We expect that DPGP with the help of CO2 laser can be an alternative to the treatment of tooth crack or fracture.

Treatment of dental root fracture by medium energy CO2 laser and DP-bioactive glass paste. Part. II: Compositional, structure, and phase changes of DP-bioglass paste after exposed to CO2 laser

Fractured teeth are difficult to treat effectively. Currently, such as root fractures are usually treated by full-coverage restoration, root amputation, or tooth extraction. If the fusion of tooth fracture by laser were possible, it could offer a different therapy to repair fracture teeth. We tried to use a developed DP-bioactive glass paste to fuse or bridge the tooth crack line by a medium energy continuous-wave CO2 laser. The present report was focused on the phase transformation and rescrystallization of DP-bioactive paste during expose to the CO2 laser. The materials will examine by means of XRD, FTIR, DTA/TGA, and SEM. From the study, we could expect that the temperature increase due to laser irradiation must be over than 900 degrees C and the DP-bioactive glass paste could be melted in a short period of time after irradiation. In the study, we successfully developed a DP-bioactive glass paste which could form a melting glass within minutes after exposed to a medium energy density continuous-wave CO2 laser. The paste will be used to bridge the enamel or dentine surface crack by the continuous-wave CO2 laser in the near future.

Treatment of tooth fracture by medium energy CO2 laser and DP-bioactive glass paste: thermal behavior and phase transformation of human tooth enamel and dentin after irradiation by CO2 laser

Acute trauma or trauma associated with occlusal disharmony can produce tooth crack or fracture. Although several methods are proposed to treat the defect, however, the prognosis is generally poor. If the fusion of a tooth fracture by laser is possible it will offer an alternative to extraction or at least serve as an adjunctive treatment in the reconstruction. The responses of soft tissues to lasers of different wavelengths are fairly well known, but the reactions of hard tissues are still to be understood. The purpose of this research was to study the feasibility of using a medium energy continuous-wave CO(2) laser and a low melting-point bioactive glass to fuse or bridge tooth fractures. The present report is focused on the first part of the research, the analysis of changes in laser-irradiated human tooth enamel/dentin by means of X-ray diffractometer (XRD), Fourier-transforming infrared spectroscopy (FTIR), differential thermal analysis/thermogravimetric analysis (DTA/TGA), and scanning electron microscopy (SEM). After CO(2) laser irradiation, there were no marked changes in the X-ray diffraction pattern of the enamel when compared to that before laser treatment. However, a small peak belonging to alpha-TCP appeared at the position of 2theta=30.78 degrees C. After being treated with CO(2) laser, the dentin showed much sharper peaks on the diffraction patterns because of grain growth and better crystallinity. alpha-TCP and beta-TCP were identified after laser treatment. In the FTIR analysis, an HPO(4)(-2) absorption band was noted before laser treatment disappeared after the irradiation. No significant change in the absorption band of HPO(4)(-2) was found on the FTIR curves of enamel after laser treatment. The results of DTA/TGA indicated that loss of water and organic materials occurred in both enamel and dentin after laser treatment. Under SEM, melting and resolidification occurred in both enamel and dentin by medium energy of CO(2) laser. This implies that using a continuous-wave CO(2) laser of medium energy density to fuse a low melting-point bioactive glass to the enamel/dentin is possible. We believe these phase changes and thermal data can make a useful guide for future studies on the thermal interaction and bridging mechanism between the bioactive glass and enamel/dentin under CO(2) laser irradiation.

Treatment of tooth fracture by medium energy CO2 laser and DP-bioactive glass paste: compositional, structural, and phase changes of DP-bioglass paste after irradiation by CO2 laser

Nowadays, fractured teeth are difficult to treat effectively. Currently, root fractures are usually treated by root amputation, hemisection or tooth extraction. If the fusion of tooth fracture by laser were possible, it would offer a different therapy to repair fracture teeth. We tried to use a developed DP-bioactive glass paste to fuse or bridge the tooth crack line by a medium energy continuous-wave CO2 laser. The study is divided into three parts: (1) The compositional and structure changes in tooth enamel and dentin after laser treatment; (2) The phase transformation and recrystallization of DP-bioactive paste during exposure to the CO2 laser; (3) The thermal interactions and bridge mechanism between DP-bioactive glass paste and enamel/dentin when they are subjected to CO2 laser. The present report will focus on the second part that will examine the changes of laser-exposed DP-bioactive glass paste by means of X-ray diffractometer (XRD), Fourier transforming infrared spectroscopy (FTIR), differential thermal analysis/thermogravimetric analysis (DTA/TGA), and scanning electron microscopy (SEM). From the study, we could find that the temperature increase due to laser irradiation is greater than 900 degrees C and that the DP-bioactive glass paste could be melted in a short period of time after irradiation. In the study, we successfully developed a DP-bioactive glass paste which could form a melting glass within seconds after exposure to a medium energy density continuous-wave CO2 laser. The paste will be used in the near future to bridge the enamel or dentin surface crack by the continuous-wave CO2 laser.

In vivo evaluation of 2-cyanoacrylates as surgical adhesives

To evaluate 2-cyanoacrylates as surgical adhesives, the bond strength in vivo as well as the tissue reaction was investigated using methyl-, ethyl-, isobutyl-, and ethoxyethyl-2-cyanoacrylate. In addition, their set time and spreading on blood were studied. When the 2-cyanoacrylates were applied to an incised site of rabbit skin, they could maintain the skin closure without suturing during the first week and the bond strength increased during the second week. Significant inflammatory response was observed around the subcutaneous tissue glued with methyl- and ethoxyethyl-2-cyanoacrylate and persisted for approximately one week. All the 2-cyanoacrylate polymers were absorbed and the tissues treated were healed two weeks after the operation. There was a mild inflammatory reaction in the tissue treated with ethyl- and isobutyl-2-cyanoacrylate, and their polymers still remained at the wound site at the second week postoperatively. The disappearance rate of the 2-cyanoacrylate polymers was roughly in proportion to the inflammatory tissue response. Ethoxyethyl-2-cyanoacrylate spread more broadly on tissues than the other 2-cyanoacrylates, while its set time was shorter than that of methyl- and ethyl-2-cyanoacrylates.

Preparation and release properties of biodegradable chitin microcapsules: II. Sustained release of 6-mercaptopurine from chitin microcapsules

Chitin microcapsules are prepared using a simple desolvation or nonsolvent addition phase separation method with 6-mercaptopurine (6-MP) as a reference core. Chitin with a molecular weight about 400,000 is used to prepare different core loaded microcapsules. The drug release rates of chitin microcapsules prepared by simple desolvation or nonsolvent addition method have different release profiles which are related to the rate of phase separation. With respect to the solubility parameter difference (delta delta) value between solvent and nonsolvent, the release rate of 6-MP from microcapsules decreases with increasing delta delta of the preparative system. The chitin beads show poor swelling properties and their release rates are pH-dependent. Sustained release of 6-MP from chitin microcapsules in low pH and neutral medium can be accomplished. To determine if the drug release from the polymer matrix is via a diffusion controlled or by an erosion controlled process, 6-MP release profiles of various chitin microcapsules degraded by lysozyme are investigated. The drug-release patterns of the chitin microcapsules prepared by nonsolvent addition (acetone, n-propanol, n-butanol) and simple desolvation in acetone are not only diffusion but also lysozyme digestion influenced. Whereas, by using water or ethanol as nonsolvent or desolvating agent, release profiles of the microcapsules prepared by nonsolvent addition and the simple desolvation method seem to be little affected by enzyme degradation. These results indicate that chitin might prove useful as a polymer carrier for the sustained release of drugs.

Preparation and release properties of biodegradable chitin microcapsules: I. Preparation of 6-mercaptopurine microcapsules by phase separation methods

Chitin [poly-(N-acetyl-1,4-beta-D-glucopyranosamine)] microcapsules were prepared by the simple desolvation and the non-solvent addition phase separation methods. In the simple desolvation method, chitin droplets were dropped into the desolvation agent (water, ethanol, or acetone) and microcapsules soon formed. Several solvent-nonsolvent pairs: N,N-dimethylacetamide (DMAc)-water, DMAc-ethanol, DMAc-propanol, DMAc-n-butanol, and DMAc-acetone with different solubility parameter difference, (delta delta) were chosen to prepare chitin microcapsules containing 6-mercaptopurine by using the non-solvent-addition phase separation method. The results showed that the surface morphology and release behaviour of the microcapsules were greatly affected by different solvent-nonsolvent pairs. The surface of microcapsules prepared from the system of high delta delta was more smooth than those from the systems of low delta delta. The drug content using the simple desolvation method increased with decreasing delta delta because of the higher film formation rate of the microcapsules. On the other hand, the drug content using the nonsolvent addition method was lower than that using the simple desolvation method because of the dispersion forces, applied by mechanical stirring. Microcapsules prepared by the simple desolvation method had a narrower size distribution and larger mean size than those prepared by the nonsolvent addition method.

Grafting of ethylene glycol-butadiene block copolymers onto dimethyl-dichlorosilane-coated glass by gamma-irradiation

Amphipathic ethylene glycol-butadiene block copolymers (PEG-PB) with different chain lengths of poly(ethylene glycol) (PEG) were synthesized by reacting poly(ethylene glycol methyl ether) (m-PEG, mol. wt = 350, 550, 750, 2000 and 5000) with telechelic polybutadiene (PB). The PEG-PB copolymers formed were covalently grafted to dimethyldichlorosilane-coated glass (DDS-glass) by gamma-irradiation. The PEG-grafted surface was characterized by measuring advancing and receding contact angles, fibrinogen adsorption, the number of adherent platelets and the area of spread platelets. The grafting efficiency was measured indirectly from the ability of the surface to prevent platelet adhesion. The total dose of gamma-irradiation necessary for grafting of PEG-PB onto DDS-glass in aqueous solutions was less than 0.24 Mrad at atmospheric pressure and ambient temperature. For successful grafting, the surface-adsorbed copolymers should be gamma-irradiated in the presence of water. gamma-Irradiation in the dried state did not result in copolymer grafting. The adsorption of copolymers for 30 min before exposure to gamma-irradiation was enough for effective grafting. The grafting was equally effective whether or not DDS-glass was exposed to the air-copolymer solution interface when the DDS-glass was introduced into the copolymer solution. The copolymers were able to prevent platelet adhesion only when they were adsorbed onto DDS-glass at certain bulk concentrations. Too low or too high copolymer concentrations in the adsorption solution resulted in a surface where platelets could adhere and activate. The range of copolymer concentration which prevented platelet adhesion was larger as the PEG chain length of the grafted copolymers became longer. Our data indicate that platelet-resistant surfaces can be made by grafting PEG-PB onto chemically inert surfaces by a simple gamma-irradiation process.

Involvement of RecF pathway recombination genes in postreplication repair in UV-irradiated Escherichia coli cells

Mutations affecting the RecF pathway of recombination (recF, recG, recJ, recN, recO, recQ, recR, ruvA, ruvC) were systematically introduced into two sets of strains: (a) uvrA and uvrA recA2020, (b) uvrA recBC sbcBC and uvrA recBC sbcBC recA2020. We examined: (i) the effect of these mutations on the repair of DNA daughter-strand gaps which are produced in the nascent DNA synthesized after UV irradiation, and (ii) the ability of recA2020 (a suppressor for the recF mutation) to suppress the UV radiation sensitivity caused by these mutations. In the uvrA cells, mutations in recF, recR or recO genes produced a major deficiency in the repair of daughter-strand gaps, whereas mutations in recJ, recG, recN, recQ, ruvA or ruvC genes had no effect on the repair of daughter-strand gaps. In both uvrA and uvrA recBC sbcBC backgrounds, the UV radiation sensitivity caused by recF, recG, recR, recO, ruvA, or ruvC mutations was partially suppressed by recA2020, whereas the UV radiation sensitivity caused by recJ, recN, or recQ mutations was not suppressed by recA2020. Partial suppression of the UV sensitivity of recG, ruvA and ruvC mutants was not observed with other suppressors for recF, i.e., recA441, recA720 and recA730. Taken together, these results further support the notion that the recF, recR and recO gene products (abbreviated as RecFOR) function at the same step in recombination repair, possible as a complex. It also suggests that this putative RecFOR complex does not contain proteins encoded by other genes involved in the RecF pathway of recombination.

Albumin grafting on to polypropylene by thermal activation

4-azido-2-nitrophenyl albumin (ANP-albumin) was prepared by reacting 4-fluoro-3-nitrophenyl azide with albumin. The thermal decomposition kinetics of phenyl azide of ANP-albumin was studied at various temperatures by Fourier-Transform Infrared (FTIR) spectroscopy. The decomposition rate of the phenyl azide increased with temperature. The activation energy for the first-order decomposition of the phenyl azide was 128.0 kJ/mol. Albumin was grafted on to polypropylene (PP) films by thermolysis of the azido groups of ANP-albumin with no premodification of the PP surface. The albumin-grafted surface was characterized by electron spectroscopy for chemical analysis (ESCA) and by quantitative determination of platelet adhesion and activation. The bulk concentration of ANP-albumin used for adsorption varied from 0.001 to 30 mg ml-1, and the albumin-adsorbed PP films were incubated at 100 degrees C for up to 7 h. The carbon and nitrogen peaks resulting from the grafted albumin were used to compare the surface albumin concentrations as a function of the concentration of ANP-albumin in the adsorption solution. When the PP film was adsorbed with ANP-albumin at the concentration of 5 mg ml-1 or higher and incubated at 100 degrees C for longer than 5 h, the surface became resistant to platelet adhesion. The ANP-albumin can be grafted on to chemically inert surfaces such as PP surface through simple thermolysis of azido groups to prevent platelet adhesion and activation.

Endothelin binding to receptors and endothelin production by human thyroid follicular cells: effects of transforming growth factor-beta and thyrotropin

Measurable endothelin (ET) was found in serum-free medium of cultured primary thyroid cells derived from human thyroid tissues after 3 days incubation at levels ranging from undetectable to 35 fmol/100,000 cells. Out of 12 thyroid glands studied, 2 responded to transforming growth factor-beta (TGF-beta) treatment with increased ET secretion into medium. Detailed study of cells derived from one of these thyroids showed TGF-beta at 1 ng/ml stimulated ET secretion from 13.7 to 33.3 fmol/100,000 cells after 3 days incubation. Although TSH alone did not significantly modulate ET release into medium, TSH enhanced the stimulatory effect of TGF-beta. A combination of TSH at 1 mU/ml and TGF-beta at 1 ng/ml stimulated ET secretion to 63.8 fmol/100,000 cells after 3 days incubation. Immunostaining studies demonstrated the presence of intracellular immunoreactive ET, largely localized in perinuclear regions, which was greatly stimulated by TSH but not by TGF-beta. These observations suggest that TSH may stimulate only ET synthesis, whereas TGF-beta may stimulate both synthesis and secretion. Binding of [125I]ET-1 to receptor on thyroid cells was dose-dependently stimulated by TGF-beta (0-10 ng/ml) pretreatment for 3 days. Scatchard analysis of competitive binding data from TGF-beta (1 ng/ml)-treated cells indicated that increased binding was the result of increased receptor number and not increased receptor affinity. TSH (0-10 mU/ml), though not as potent as TGF-beta, also dose-dependently stimulated ET binding. Treatment of thyrocytes with 1 mU/ml TSH for 3 days did not significantly affect ET receptor number or binding affinity. These results illuminate aspects of a possible autocrine regulation of ET in the thyroid gland.

Photografting of albumin onto dimethyldichlorosilane-coated glass

4-Azido-2-nitrophenyl albumin (ANP-albumin) was prepared by displacing the fluoro group of 4-fluoro-3-nitrophenyl azide (FNPA) by an amino group of albumin. Photolysis of phenyl azides of ANP-albumin was studied by Fourier-transform infrared (FTIR) spectroscopy. The band of phenyl azide disappeared completely after a 12-min exposure to long wave UV light (366 nm), and the photolysis was first-order. Albumin was grafted onto dimethyldichlorosilane-coated glass (DDS-glass) by photolysis of the azido groups of ANP-albumin without any premodification of the surface. The albumin-grafted DDS-glass was characterized by determining the relative amount of nitrogen resulting from the grafted albumin on the surface using electron spectroscopy for chemical analysis (ESCA). The amount of nitrogen increased when the concentration of ANP-albumin in the adsorption solution increased up to 0.1 mg/ml. As the solution concentration increased above this value, the amount of nitrogen decreased. The platelet resistance of the albumin-grafted surfaces was evaluated by measuring the number of adherent platelets and the extent of activation that was quantitated by the area of platelets spread on the surfaces. The maximum platelet-resistant effect was observed when the ANP-albumin was adsorbed for more than 50 min at the solution concentration ranging from 0.05 to 10 mg/ml.

Atrial natriuretic peptide receptors in human endometrial stromal cells

Atrial natriuretic peptide (ANP) has been shown to affect water and ion transport and specific ANP binding has been identified in several secretory tissues. ANP commonly acts via stimulation of membrane-bound particulate guanylate cyclase with the production of cyclic guanosine monophosphate (cGMP). We questioned whether ANP played a role in the complex cyclic transformation of the endometrium into a secretory tissue, and whether its action was cGMP mediated. Endometrium was obtained by biopsy in regularly menstruating women and stromal cells were isolated and cultured for use in this study. ANP competitive binding assays were performed using 125I-labeled ANP (0.1 nmol/L) and increasing concentrations of unlabeled ANP (0-1000 nmol/L). Optimal binding was obtained after 3-h incubation at 4 C and binding characteristics, including dissociation constant and binding site quantity, were estimated by Scatchard analysis. Specific, high affinity (dissociation constant, 0.078 +/- 0.004 nmol/L) and low capacity (4,877 +/- 1,951 binding sites/cell) ANP binding was identified, with nonspecific binding representing less than or equal to 16% of total binding. Evaluation of ANP-stimulated cyclic nucleotide production revealed an increase in cGMP production, with a 7-fold increase at 1000 nmol/L ANP, and no effect on cAMP production. In conclusion, we have identified specific high affinity receptors for ANP in human endometrial cells, suggesting a role for ANP in endometrial cell function and/or development mediated via cGMP production. We propose that ANP may affect local salt and water metabolism, may be involved in the secretory evolution of glandular and stromal cells, and may further facilitate endometrial development via modulation of local vascular tone and endothelial permeability.

Receptors for endothelin in cultured human thyroid cells and inhibition by endothelin of thyroglobulin secretion

Specific receptors for endothelin-1 (ET), a newly described vasoconstrictor peptide isolated from endothelium, have been identified in endocrine tissues such as hypothalamus, adrenal and pituitary. ET binding or action, not previously described in thyroid, were explored in this study. ET binding in cultured human thyrocytes was assayed at 4 C, 25 C, and 37 C, for 0.5-6 h with [125I]ET (0.1 nmol/L), and nonspecific binding estimated by coincubation with unlabeled ET (100 nmol/L). At 4 C, maximum specific binding was reached after 4 h; at 25 C and 37 C, specific binding increased in a time-dependent manner over 6 h with increased binding obtained at higher temperature. At 37 C after 2 h, 11% specific bound ET localized to surface membranes with 89% internalized. Scatchard analysis of surface membrane binding at 4 C for 4 h showed high affinity single class ET receptor (Kd = 0.20 nmol/L) and binding capacity of 4045 sites per cell. ET binding to thyroid cells had no effect on production of cAMP or cGMP. ET (0.1 nmol/L) significantly (P less than 0.001) inhibited thyroglobulin release from thyroid cells after 6 days with no effect on thymidine incorporation. Thus, we have identified specific receptors for endothelin in human thyrocytes, and an inhibitory action of the peptide on thyroglobulin release which is mediated by a noncyclic nucleotide mechanism.

Synthesis of photoreactive poly(ethylene glycol) and its application to the prevention of surface-induced platelet activation

Photoreactive poly(ethylene glycol) (PEG) was synthesized by reacting 4-fluoro-3-nitrophenyl azide (FNPA) with sodium salt of PEG. The synthesized 4-azido-2-nitrophenyl PEG (ANP-PEG) was characterized by 1H-NMR, IR, and UV spectroscopy. ANP-PEG was grafted to dimethyldichlorosilane-coated glass (DDS-glass) by photolysis without any premodification of the surface. The effects of various grafting factors, such as the polymer adsorption time, concentration of ANP-PEG, and UV irradiation time, on the PEG grafting efficiency were examined. The PEG-grafted DDS-glass was characterized by measuring surface free energies, surface-induced platelet activation, and the relative amount of PEG grafted on the surface using electron spectroscopy for chemical analysis (ESCA). Platelet adhesion and activation was analyzed by measuring the number and spread area of adherent platelets. The results showed that ANP-PEG had to be adsorbed onto DDS-glass for at least 12 h before photolysis for the maximum grafting efficiency. No platelets could adhere to the PEG-grafted DDS-glass, if the bulk concentration of ANP-PEG in the adsorption solution was between 1 mg/mL and 10 mg/mL. Above 10 mg/mL, platelet activation gradually increased and reached the maximum at 30 mg/mL. Our data indicate that the grafting of ANP-PEG requires careful control of the grafting conditions and that the grafted PEG can prevent surface-induced platelet activation.

Thyrotropin modulation of epidermal growth factor (EGF) binding to receptors on cultured thyroid cells

Previous studies had shown that epidermal growth factor (EGF) will stimulate growth of cultured thyroid cells in vitro, and TSH will stimulate total assayable EGF receptor in cultured porcine thyroid cells. In this study, we report the effect of TSH on EGF binding to human thyroid cells. Addition of bTSH (1 mU/mL) in binding buffer during receptor assay stimulated specific EGF binding to cells, with an increase of 44% observed over the control after 1 h incubation at 37 degrees C. Affinity crosslinking of the [125I]EGF-receptor complex showed a single labeled band with molecular size of 170 kD. No additional band was detected in the presence of TSH. Preincubation of cells with chloroquine, which inhibits lysosomal degradative enzyme activity, caused a continuous accumulation of bound EGF over a 4 h study period at 37 degrees C, and TSH stimulated an increase in internalized EGF. In the presence of chloroquine, total specific bound EGF was linearly correlated to incubation time up to 4 h and can be expressed as Bound = slope*time+intercept (time0) Addition of TSH during the binding assay significantly increased the value of the slope when compared to control (p < 0.002). The rate at which prebound [125I]EGF was released into medium was not affected by the presence of TSH, indicating that TSH-enhanced binding may not be attributed to a reduction in EGF degradation. Coincubation of thyroid cells with EGF at 0 and 1 ng/mL and increasing concentrations of TSH (0-10 mU/mL) indicated that EGF stimulated thymidine incorporation, although TSH failed to synergistically enhance EGF-stimulated cell growth.(ABSTRACT TRUNCATED AT 250 WORDS)

Inhibition of TSH activation of human cultured thyroid cells by tumor necrosis factor: an explanation for decreased thyroid function in systemic illness?

Thyroidal economy in systemic nonthyroidal illness (the sick euthyroid syndrome) is marked by reductions in both thyroid function and peripheral T4 to T3 conversion, presumed to reflect a homeostatic mechanism to conserve energy. TSH levels tend to be normal in these patients, and the mechanism underlying reduced thyroidal secretion is unknown. Since increased blood levels of tumor necrosis factor (TNF) are found in many of the conditions associated with the sick euthyroid syndrome, we hypothesized that TNF might affect the function of the thyroid gland. We, therefore, explored the effects of TNF on TSH stimulation of the thyroid, employing a human thyrocyte cell culture model. Cells were incubated with various concentrations (0-1000 pg/mL) of recombinant human TNF-alpha and bTSH (1 mU/mL), with measurement of secreted thyroglobulin (Tg) and cyclic AMP (cAMP) as the end points of stimulation. TNF had no effect on either basal or TSH-stimulated cAMP generation, but significantly blunted TSH-stimulated Tg secretion. No loss of cell viability and growth was observed based on trypan blue exclusion and thymidine incorporation by cells. These studies demonstrated an inhibitory effect on TNF on human thyrocytes in concentrations comparable to blood levels seen in humans during systemic illness. We conclude that increases in serum TNF may be responsible for reduced thyroid function in patients with the sick euthyroid syndrome.

In vitro toxicity test of 2-cyanoacrylate polymers by cell culture method

The inhibition of Swiss 3T3 cell growth by the microspheres prepared from various 2-cyanoacrylate polymers was investigated to assess their cell toxicity. Poly(ethoxy-ethyl 2-cyanoacrylate) and poly(methyl 2-cyanoacrylate) microspheres inhibited cell growth in a smaller amount than poly-(isobutyl 2-cyanoacrylate) and poly (ethyl 2-cyanoacrylate) microspheres. The extent of cell growth inhibition by the microspheres decreased with the increasing molecular weight, regardless of the kind of polymers used. Every kind of the microspheres was degraded releasing formaldehyde in the culture medium. The cell growth inhibition by the medium containing the microspheres was observed within 24 h for poly(ethoxyethyl 2-cyanoacrylate) and poly(methyl 2-cyanoacrylate). The extent of inhibition was in a linear proportion with the amount of formaldehyde released. It is concluded that the cell toxicity of 2-cyanoacrylate polymers is attributed to formaldehyde released upon polymer degradation.

Characterization by affinity cross-linking of a receptor for atrial natriuretic peptide in cultured human thyroid cells associated with reductions in both adenosine 3',5'-monophosphate production and thyroglobulin secretion

We have previously identified specific atriopeptin (ANP) receptors in cultured human thyroid cells and demonstrated that ANP reduced thyroglobulin (Tg) secretion. In this report the relationship of Tg inhibition to cyclic nucleotide intermediate pathways was explored, and the thyroidal ANP receptor was characterized by affinity cross-linking. Concentrations of Tg, cGMP, and cAMP were measured in medium from thyroid cells cocultured with ANP. ANP significantly inhibited cAMP production at the lower concentration of 0.1 nmol/L and stimulated cGMP levels at a higher concentration of 10 nmol/L. The percentage of inhibition of Tg release over the ANP range of 0.01-10 nmol/L appeared to parallel cAMP, but not cGMP, levels, suggesting that ANP acts via a cAMP pathway in the thyroid. Affinity cross-linking studies characterizing the ANP receptor in thyrocytes and a bovine endothelial cell line known to be cGMP responsive to ANP indicated a single unit ANP receptor of 140 kD coupled to guanylate cyclase in endothelial cells, while a 70-kD receptor was found in thyroid cells which specifically binds to ANP, atriopeptin-I, and atriopeptin-III. These studies in thyrocytes suggest that reduced Tg release may be mediated by a specific single 70-kD ANP receptor associated with an inhibitor cAMP pathway and provide additional insight into the nature of a newly described thyroid-ANP interaction.

Modified ethoxyethyl cyanoacrylate for therapeutic embolization of arteriovenous malformation

Aiming at alleviating the problems of using 2-cyanoacrylates as a material for therapeutic embolization, this experiment made some physical modifications by mixing contrast media. It was found that the physicochemical properties of 2-cyanoacrylates can be altered by changing the concentration and the composition of the contrast media added. A 50 wt% cyanoacrylate-50 wt% contrast medium mixture has enough radiopacity for the practical requirement for embolization. A mixture of 50 wt% (ethoxyethyl cyanoacrylate-5 wt% lactide/epsilon-caprolactone copolymer), 25 wt% lipiodol and 25 wt% tetrafluorodibromoethane provides a viscosity of 13.8 cP, a bonding strength of 14.9 kg/cm2, a set time of 6 s, and a spreading in canine blood of 33 mm. It was concluded that the mixture is much more satisfactory than the conventional cyanoacrylates as an embolus material in vitro. The results obtained by in vivo experiments and clinical trials so far suggest that the mixture is very promising as a material for embolization.

Modification of synthesis and investigation of properties for 2-cyanoacrylates

The conventional method for synthesis of 2-cyanoacrylate monomers was modified and the adhesive properties were studied for the cyanoacrylate monomers and the resultant polymers. Toluene was found to be better as reaction solvent than methyl alcohol or xylene. The higher the molecular weight of the condensation oligomer before pyrolysis and the narrower the molecular weight distribution, the higher the yield of cyanoacrylate monomer. Ethoxyethyl cyanoacrylate with an ether side chain was shown to be a soft and biodegradable adhesive. The softening and glass transition temperatures of ethoxyethyl cyanoacrylate polymer were much lower than those of cyanoacrylate polymers with methyl, ethyl or isobutyl side chains. Hydrolysis of poly(ethoxyethyl cyanoacrylate), evaluated from formaldehyde generation and mass loss, was faster than that of ethyl cyanoacrylate and isobutyl cyanoacrylate polymer. Hydrolysis of the ethoxyethyl cyanoacrylate polymers was greatly affected by the molecular weight of the polymers. The morphological change of the cyanoacrylate polymer films was studied by scanning electron microscopy.

Effects of epidermal growth factor on thyroglobulin and adenosine 3',5'-monophosphate production by cultured human thyrocytes

While several workers have identified epidermal growth factor (EGF) receptors on human thyroid membranes, very few reports have described EGF effects on intact human thyroid cells in primary culture, and these were short term studies indicating that EGF effects were primarily inhibitory [reduced iodide uptake and thyroglobulin (Tg), T4, and T3 release]. Paradoxically, in vivo EGF stimulates thyroid growth and increases colloid stores. In this study we examined the effects of EGF on cultured thyroid cells in regard to thymidine incorporation, Tg secretion, and cAMP production during a 12-day period. Addition of EGF (0-30 ng/mL) to medium for 6 or 12 days stimulated thymidine incorporation and enhanced Tg synthesis by thyroid cells. However, the profile of Tg release into medium was biphasic. Tg release was inhibited by EGF (0.1-10 ng/mL) during the first 3 days of culture, but the inhibitory effect disappeared by the sixth day, and EGF stimulated Tg release by day 12 and thereafter. EGF enhanced endogenous cAMP levels in thyroid cells, but did not augment TSH-stimulated increases in cAMP production. Our observations of EGF-stimulated growth and inhibited Tg secretion during short term culture are consistent with the findings of earlier studies with nonhuman thyrocytes. However, the later phase of enhanced cAMP levels with stimulation of Tg secretion indicates that EGF may have trophic effects on thyrocytes previously unrecognized because of the short term nature of the studies. These observations suggest an important role for EGF in maintenance of normal thyroid physiology.

Thyrotropin modulates receptors for atrial natriuretic peptide on intact human thyroid cells

Interest in the mechanism of impaired salt and water metabolism in hypothyroidism has led to growing evidence of an interaction between atrial natriuretic peptide (ANP) and the thyroid, which includes reports of direct effects of thyroid hormone on ANP synthesis and circulating ANP levels, and of the presence of specific ANP receptors in human thyroid tissue, which may act to inhibit thyroglobulin (Tg) secretion. The authors questioned whether or not thyrotropin (TSH) has a role in this interaction. They used 125I-ANP to study the effect of TSH on ANP binding to human thyroid cells in primary culture. Binding competition by increasing concentrations of unlabeled ANP in the presence or absence of TSH was assessed by Scatchard analysis. At lower temperatures of 4 degrees C or 23 degrees C, TSH had no effect either on the ANP receptor equilibrium dissociation constant (Kd) or number of binding sites. However, at 37 degrees C, bovine TSH at 1 mU/ml reduced measurable binding sites by about 50% without affecting receptor affinity (Kd = 0.2 nM). Prolonged (6 days) coincubation of TSH with thyroid cells decreased the assayable ANP receptor. The effects of TSH appear to be specific because human luteinizing hormone, follicle-stimulatory hormone, growth hormone, human chorionic gonadotropin and iodide had no effect on ANP binding. Thus, human thyroid cells possess a single class of high-affinity, specific receptors for ANP with binding activity that is temperature dependent and modulated by TSH at physiologic temperature. TSH-mediated reduction of binding at 37 degrees C but not at 4 degrees C suggests an energy-dependent process that acts possibly by activating an ANP degradative enzyme or by changing the rate of receptor internalization and subsequent degradation.

Receptors for atrial natriuretic peptide (ANP) and regulation of thyroglobulin secretion by ANP in human thyroid cells

Specific binding sites for atrial natriuretic peptide (ANP) were identified and characterized in primary cultures of human thyroid cells. Saturation analysis using [125I] alpha rat ANP as the ligand showed a single class of high affinity binding (Kd = 0.2 nM) which was inhibited by atriopeptin I and the alpha -human form of ANP, but not by a C-terminal fragment of the peptide. The number of ANP binding sites in these cultures was not altered by the thyroid hormone concentration of the medium. In a dose-response experiment, thyro-globulin secretion was significantly reduced in the presence of 0.01 nM ANP and was maximally reduced (to 25% of control value) with 10 nM ANP. Cyclic GMP production was increased threefold in the presence of 100 nM ANP, but was unchanged with lower doses (0.01 and 0.1 nM) of the peptide. The finding of receptors in thyroid follicular cells suggests a hitherto unrecognized role of ANP in the thyroid gland.

Seronegative Hashimoto thyroiditis with thyroid autoantibody production localized to the thyroid

A patient without serologic evidence of an autoimmune disorder had a thyroidectomy for neck compression caused by her goiter. Histologic examination of the gland revealed pathologic changes compatible with Hashimoto disease, and lymphocytes isolated from her thyroid gland were transformed into lymphoblastoid cells in vitro by Epstein-Barr virus in the presence of cyclosporine. These cells produced antibodies against thyroglobulin, thyroid microsome, thyrocyte membrane, and thyrotropin, whereas lymphoblastoid cells produced from the patient's peripheral blood lymphocytes showed no antithyroid activity. Several human monoclonal antibodies were produced from the intrathyroidal lymphocytes by fusion with the SHM-D33 heteromyeloma, and the resulting cell lines produced antibodies with high-affinity binding specific for thyroid antigens. These studies show that lymphocytes capable of producing antithyroid antibodies can be present in the thyroid glands of patients with Hashimoto disease without evidence of a peripheral immune response, thus indicating that Hashimoto disease can exist as an organ-restricted autoimmune disorder.

Intrinsic abnormality of thyroid cells from a patient with a Brobdingnagian goiter

Thyrocytes from normal and goitrous portions of the thyroid gland from a patient with an enormous (635 gm) goiter were cultured in media, and their relative abilities to uptake thymidine, synthesize DNA, and secrete Tg and T4 were assessed. Tg, T4 and the ratio Tg/T4 in media at 72 h were 120 micrograms/dl, 1.6 micrograms/dl and 75 for normal cells, and 410 micrograms/dl and 273 for goitrous cells. DNA synthesis was 30-100% greater in goitrous than normal cells over a period of 72 h indicating abnormally high rates of cell division and growth, but their thymidine uptake was only 20% of that in normal cells. TSH elicited stimulation of thymidine uptake and DNA synthesis both in goitrous and in normal cells, but to a lesser extent in goitrous cells. No evidence of growth stimulating autoantibody activity was detected in the patient's serum. These data indicate that although the ability of goitrous cells to uptake thymidine was impaired, their DNA synthesis was more active than normal thyroid, which may have led to disordered cell growth as evidenced by the enormous goiter size in this patient. Although goitrous cells secreted more than three times as much Tg into media compared to normal, media T4 levels were similar, indicating an increased synthesis yet low iodination of Tg in goitrous cells. There does not appear to be any support for TGSI mediation of the goiter in this patient, but rather, the goiter may have been due to an intrinsic alteration in DNA synthesis resulting in vigorous cell growth.

L-thyroxine dosage: a reevaluation of therapy with contemporary preparations

Traditional L-thyroxine dosing formulas may overestimate the thyroid hormone requirement in patients treated with contemporary L-thyroxine preparations. We did clinical and laboratory assessments of 41 patients treated in successive periods with Levothroid (Armour Pharmaceuticals, Kankakee, Illinois) and Synthroid (Flint Division, Travenol Laboratories, Morton Grove, Illinois), obtaining 87 sets of data. Clinical subgroups were defined on the basis of the thyrotrophin response to thyrotrophin-releasing hormone. Normal responses were seen in 9 of 14 (64%) patients taking 100 micrograms/d and were associated with an average replacement dosage of 127 micrograms/d (1.7 micrograms/kg body weight). Nine of twenty-eight (32%) serum thyroxine values in the "physiologically replaced" group were elevated. Forty-three of fifty-four (80%) patients ingesting 125 micrograms or more had blunted responses (thyroxine "overreplaced"), averaging a daily dosage of 154 micrograms (2.14 micrograms/kg X d). No significant difference was found between Levothroid and Synthroid in predicting clinical group assignment. Guidelines for currently available L-thyroxine preparations should be revised and the recommended dosage reduced.

A rapid, sensitive enzyme-linked immunoassay for human thyrotropin

In this enzyme-linked immunoassay for human thyrotropin (TSH) in unextracted serum we use 96-well immunoenzymometric assay plates, first coated with polyclonal antibody to TSH, then incubated with the serum samples and reacted with mouse monoclonal antibody to human TSH. After incubation with alkaline phosphatase-labeled antibody against mouse IgG, disodium p-nitrophenyl phosphate is added and the color change is measured spectrophotometrically. Assay sensitivity is 0.1 milli-int. unit/L. Cross reactivity with lutropin, follitropin, or choriogonadotropin was negligible. TSH concentrations ranged from 0.4 to 4.1 milli-int. units/L in 43 normal subjects (mean 2.0, SD 1.0), and were uniformly less than 0.3 milli-int. unit/L in 23 patients with hyperthyroidism. Features which make this assay advantageous to the clinical laboratory include ease of set-up, ability to assay many samples at a time, high sensitivity, rapid turnaround time (8 h), and absence of requirements for radioactive materials.

A rapid, sensitive enzyme-linked immunoassay for human thyrotropin

In this enzyme-linked immunoassay for human thyrotropin (TSH) in unextracted serum we use 96-well immunoenzymometric assay plates, first coated with polyclonal antibody to TSH, then incubated with the serum samples and reacted with mouse monoclonal antibody to human TSH. After incubation with alkaline phosphatase-labeled antibody against mouse IgG, disodium p-nitrophenyl phosphate is added and the color change is measured spectrophotometrically. Assay sensitivity is 0.1 milli-int. unit/L. Cross reactivity with lutropin, follitropin, or choriogonadotropin was negligible. TSH concentrations ranged from 0.4 to 4.1 milli-int. units/L in 43 normal subjects (mean 2.0, SD 1.0), and were uniformly less than 0.3 milli-int. unit/L in 23 patients with hyperthyroidism. Features which make this assay advantageous to the clinical laboratory include ease of set-up, ability to assay many samples at a time, high sensitivity, rapid turnaround time (8 h), and absence of requirements for radioactive materials.

Nuclear thyroid hormone receptors in C3H/HeN mouse mammary glands and spontaneous tumors

Saturable, high-affinity binding sites for 3,5,3'-triiodo-L-thyronine (T3) were identified in isolated nuclei and solubilized chromatin extracts of mammary glands, spontaneous mammary tumors, and liver from C3H/HeN mice. Receptor concentration in whole mammary gland nuclei (254 fmol/mg DNA) was only about one-half that of mouse liver nuclei (536 fmol/mg DNA), but in molecular weight (55,000) and in their affinity for various thyroid hormone analogues, the binding was essentially identical. Saturation analysis of T3 binding in a series of individual spontaneous mammary tumors and pooled lactating mammary glands indicated that the concentrations of T3-binding sites of the mammary gland are conserved in the transition to neoplasms and are somewhat increased in the largest tumors. Thyroxine binding was identical in capacity to T3 binding in mammary gland nuclei and nuclear extract but showed a higher binding capacity than did T3 in the largest tumors. High-performance molecular exclusion chromatography did show a difference between mammary gland and liver in the distribution of competible [125I]T3 binding between two macromolecular forms; the excluded peak (Mr greater than 450,000) comprised 56% of the T3 binding in the liver but only 9% in the mammary gland with the included peak (Mr 55,000) contributing the balance of binding in each case. Spontaneous mammary tumor resembled the mammary gland in the macromolecular distribution of specific T3 binding (16% excluded). Thymidine uptake showed only a modest decrease in the larger tumors (greater than 2.0 g), while nuclear histone acetylase activity was significantly decreased in this group. Neither measurement showed a significant correlation with T3 or thyroxine binding capacity.

Effect of 3,5,3'-triiodo-L-thyronine on the incidence and growth kinetics of spontaneous mammary tumors in C3H/HeN mice

The present study compares the incidence and growth kinetics of spontaneous mammary tumors in 3,5,3'-triiodo-L-thyronine (T3)-treated (0.7 microgram/day, i.p.) C3H/HeN retired breeder mice with tumors occurring spontaneously in this strain (0.15 M NaCl, i.p.). T3 treatment markedly increased the rate of tumor incidence but had no effect on tumor growth rate as measured by tumor doubling time. A comparison of tumor labeling index and mitotic index between the two groups showed no difference. A histological comparison of the mammary glands in the two groups showed no significant difference in number of hyperplastic alveolar nodules. However, ductal-alveolar development was more pronounced in the 0.15 M NaCl-treated control group; consistent with this observation was the finding of lower levels of serum prolactin in the T3-treated groups. Since mammary tumorigenesis was increased in T3-treated mice in spite of lower levels of serum prolactin, a well-known promoter of spontaneous mammary tumors in mice, a direct role for T3 in the process of tumor formation is suggested.

Solubilized nuclear thyroid hormone receptors in circulating human mononuclear cells

In order to assess iodothyronine receptor interactions in man, we have developed a receptor assay for T3 and T4 in solubilized nuclear extracts from circulating mononuclear cells. This assay utilizes the technique of salt solubilization to isolate nuclear receptors and employs standard saturation analysis for T3 and T4 to determine maximal binding capacity (MBC) and equilibrium dissociation constants (Kd). We have determined that 11 normal subjects had a MBC for T3 of 1.20 +/- 0.20 pmol/mg DNA (+/- SE) and a Kd of 3.4 +/- 0.2 X 10(-10) M; the T4 MBC was 8.44 +/- 1.22 pmol/mg DNA and the Kd was 2.7 +/- 0.3 X 10(-10) M. Hypothyroid patients had a mean T3 MBC of 7.32 +/- 2.28 pmol/mg DNA and a mean T4 MBC of 40.04 +/- 21.36 pmol/mg DNA (P less than 0.05 compared to normal). Obese subjects (n = 12) had a basal fed MBC that was 0.66 +/- 0.13 pmol/mg DNA for T3 (P less than 0.05 compared to normal) and was 3.58 +/- 0.56 pmol/mg DNA for T4 (P less than 0.01 compared to normal). During fasting, the average T3 MBC increased to 1.43 +/- 0.31 pmol/mg DNA and the average T4 MBC increased to 9.63 +/- 2.46 pmol/mg DNA, values that are both significantly higher than those in the fed period; the dissociation constants were unaltered in obese subjects (compared to normals) in fed and fasting states. Gel filtration with 0.5 M agarose was employed to ascertain if the physicochemical properties of the solubilized mononuclear human cell receptor were similar to those previously observed in rat and human liver and kidney receptors. The elution profile obtained was similar to that reported earlier. The major binding activity has an estimated Stokes radius of 35 A and a molecular weight ratio of approximately 50,000 daltons. These studies indicate that: 1) high affinity T3 and T4 receptors exist in human mononuclear cells and have properties similar to those for T3 and T4 described previously in rat liver; 2) T3 and T4 receptor number tends to increase in hypothyroid subjects and tend to be lower in obese patients than in normal weight control subjects; 3) fasting is associated with an increase in both T3 and T4 MBC; and 4) despite their apparent physicochemical similarity, T3 receptors in rat liver and human mononuclear cells may be regulated differently, at least during fasting since hepatic T3 receptors decrease in the fasted rat. Collectively, these observations support the concept that human white cell T3 nuclear receptor binding is capable of rapid fluctuations, suggesting a mechanism for homeostatic regulation of T3 action.