Dissolution of ZnO nanoparticles at circumneutral pH: a study of size effects in the presence and absence of citric acid

Understanding size-dependent processes, including dissolution, of engineered nanoparticles is essential in addressing the potential environmental and health impacts of these materials as well as their long-term stability. In this study, experimental measurements of size-dependent dissolution of well-characterized zinc oxide (ZnO) nanoparticles with particle diameters in the range of 4 to 130 nm have been measured at circumneutral pH (pH 7.5) and compared. Dissolution was found to be enhanced with smaller ZnO nanoparticles compared to larger-sized particles, even though the nanoparticles were present in solution as aggregates with hydrodynamic diameters on the order of 1-3 μm in size. The presence of citric acid significantly enhanced the extent of ZnO dissolution for all sizes, and the greatest enhancement was observed for the 4 nm particles. Although these results are found to be in qualitative agreement with theoretical predictions, a linearized form of the Kelvin equation to calculate a surface free energy yielded quantities inconsistent with expected values from the literature. Reasons for this inconsistency are discussed and include potential deviations of solubility behavior from classical thermodynamics as a result of a lack of detailed knowledge of surface structure and surface properties, including the presence of different surface crystal facets, and the aggregation state.

Effects of ammonia on the structure of the oxygen-evolving complex in photosystem II as revealed by light-induced FTIR difference spectroscopy

NH(3) is a structural analogue of substrate H(2)O and an inhibitor to the water oxidation reaction in photosystem II. To test whether or not NH(3) is able to replace substrate water molecules on the oxygen-evolving complex in photosystem II, we studied the effects of NH(3) on the high-frequency region (3750-3550 cm(-1)) of the S(2)Q(A)(-)/S(1)Q(A) FTIR difference spectra (pH 7.5 at 250 K), where OH stretch modes of weak hydrogen-bonded active water molecules occur. Our results showed that NH(3) did not replace the active water molecule on the oxygen-evolving complex that gave rise to the S(1) mode at ~3586 cm(-1) and the S(2) mode at ~3613 cm(-1) in the S(2)Q(A)(-)/S(1)Q(A) FTIR difference spectrum of PSII. In addition, our mid-frequency FTIR results showed a clear difference between pH 6.5 and 7.5 on the concentration dependence of the NH(4)Cl-induced upshift of the S(2) state carboxylate mode at 1365 cm(-1) in the S(2)Q(A)(-)/S(1)Q(A) spectra of NH(4)Cl-treated PSII samples. Our results provided strong evidence that NH(3) induced this upshift in the spectra of NH(4)Cl-treated PSII samples at 250 K. Moreover, our low-frequency FTIR results showed that the Mn-O-Mn cluster vibrational mode at 606 cm(-1) in the S(2)Q(A)(-)/S(1)Q(A) spectrum of the NaCl control PSII sample was diminished in those samples treated with NH(4)Cl. Our results suggest that NH(3) induced a significant alteration on the core structure of the Mn(4)CaO(5) cluster in PSII. The implication of our findings on the structure of the NH(3)-binding site on the OEC in PSII will be discussed.

Two novel DAX1 gene mutations in Chinese patients with X-linked adrenal hypoplasia congenita: clinical, hormonal and genetic analysis

Mutations in the DAX1 gene result in X-linked congenital adrenal hypoplasia (AHC). Affected boys usually present with primary adrenal failure in early infancy or childhood and hypogonadotropic hypogonadism (HH) at puberty. This paper describes the clinical, hormonal, radiological, and genetic characteristics of 2 Chinese patients with X-linked AHC. Primary adrenal insufficiency occurred in the 2 patients during their childhood and HH was recognized at puberty. Genomic DNA was extracted from their peripheral blood leukocytes and coding sequence abnormalities of the DAX1 gene were assessed by PCR and direct sequencing analysis. Genetic analysis of the DAX1 gene revealed 2 novel mutations c.572-575 dupGGGC, p.Thr193Gly,fs,205X and c.773- 774 dupCC, p.Ser259Pro,fs,264X in exon 1, causing frameshifts and yeilding premature stop codons at 205 and 264, respectively. This study identifies 2 novel mutations in the DAX1 gene which can further expand the mutation database and benefit patients in the diagnosis and treatment of AHC.

Size-, and shape-selective synthesis of platinum nanoparticles from Pt(beta-diketonate)2 complexes in organic media

Preparation of platinum nanoparticles from two beta-diketonate complexes of platinum, Pt(hfac)2 and Pt(acac)2 (hfac: hexafluoroacetylacetonate, acac: acetylacetonate) in organic media will be presented in the contribution. Nearly spherical, well-dispersed platinum nanoparticles were fabricated by thermally-induced reduction of Pt(hfac)2 in the presence of teraalkylammonium salts as the stabilizing agents in several organic solvents. Particle sizes ranging from 9 to 15 nm can be controlled by variation of the surfactant, the concentrations of precursor and surfactant, as well as reaction temperature. Heating the solution of Pt(acac)2 complex in 1-octanol at appropriate temperatures provided the platinum nanocubes and the influence of reaction temperature on the particle shape was investigated.

Identification and characterization of a cytochrome b559 Synechocystis 6803 mutant spontaneously generated from DCMU-inhibited photoheterotrophical growth conditions

We identified a spontaneously generated mutant from Synechocystis sp. PCC6803 wild-type cells grown in BG-11 agar plates containing 5 mM Glu and 10 microM DCMU. This mutant carries an R7L mutation on the alpha-subunit of cyt b559 in photosystem II (PSII). In the recent 2.9 A PSII crystal structural model, the side chain of this arginine residue is in close contact with the heme propionates of cyt b559. We called this mutant WR7Lalpha cyt b559. This mutant grew at about the same rate as wild-type cells under photoautotrophical conditions but grew faster than wild-type cells under photoheterotrophical conditions. In addition, 77 K fluorescence and 295 K chlorophyll a fluorescence spectral results indicated that the energy delivery from phycobilisomes to PSII reaction centers was partially inhibited or uncoupled in this mutant. Moreover, WR7Lalpha cyt b559 mutant cells were more susceptible to photoinhibition than wild-type cells under high light conditions. Furthermore, our EPR results indicated that in a significant fraction of mutant reaction centers, the R7Lalpha cyt b559 mutation induced the displacement of one of the axial histidine ligands to the heme of cyt b559. On the basis of these results, we propose that the Arg7Leu mutation on the alpha-subunit of cyt b559 alters the interaction between the APC core complex and PSII reaction centers, which reduces energy delivery from the antenna to the reaction center and thus protects mutant cells from DCMU-induced photo-oxidative stress.

Association of SNPs in exon 2 of the MHC B-F gene with immune traits in two distinct chicken populations: Chinese Beijing-You and White Leghorn

Antibody titers raised for vaccinations against avian influenza (AI) and Newcastle disease (ND) were higher in Chinese Beijing-You (BJY) than in White Leghorn (WL) (P < 0.001), but there was no breed difference in titers for sheep red blood cells (SRBC). Genotyping by PCR-SSCP identified seven haplotypes in WL and 17 in BJY. After sequencing PCR products (35 and 85, respectively), 43 (WL) and 47 (BJY) single nucleotide polymorphisms (SNPs) were found in the 264 bp of exon 2. In WL chickens, significant associations were found with antibody responses to AI (two SNPs), ND (six SNPs), and SRBC (one SNP), while in BJY there was association with responses to ND (two SNPs) and SRBC (two SNPs), but none with AI. These results indicate that the genomic region bearing exon 2 of the major histocompatibility complex B-F gene has significant effects on antibody responses to SRBC and vaccination against AI and ND. Different SNPs affected antibody titers for each of the antigens and they differed between these very distinct breeds.

Effect and mechanism of andrographolide on the recovery of Pseudomonas aeruginosa susceptibility to several antibiotics

Effectiveness and mechanism of action of andrographolide on the recovery of Pseudomonas aeruginosa susceptibility to antibiotics was investigated. In the presence of andrographolide, the Mueller-Hinton broth dilution method measured minimal inhibitory concentrations (MIC) of ceftazidine, cefpirome, chloramphenicol, L-ofloxacin, kanamycin, imipenem and meropenem. Real-time fluorescence quantitative polymerase chain reaction was used to determine mexB mRNA expressions in P. aeruginosa PAO1 strain and MexAB-OprM overexpressing strain. Relative mexB mRNA expression was detected in both strains incubated for 3 and 9 h. When andrographolide-treated groups were compared with controls, the MIC of ceftazidine, cefpirome, L-ofloxacin and meropenem for both strains decreased, and the relative mexB mRNA expression was significantly lower, although between andrographolide groups there were no significant differences. Compared with the inactivated quorum-sensing system, relative amounts of mexB mRNA in the PAO1 strain and MexAB-OprM overexpressing strain in the activated quorum-sensing system increased 10- and 30-fold, respectively. Andrographolide recovered P. aeruginosa susceptibility to antibiotics and reduced the MexAB-OprM efflux pump expression level.

[Multiple focal cortical dysplasias presenting with intractable epilepsy: case report]

A 14-year-old female, who had intractable epilepsy associated with multiple focal cortical dysplasias (FCD), was reported. She developed intractable epilepsy at the age of 7 and was diagnosed as having frontal lobe epilepsy based on the seizure semiology and interictal EEG. MRI revealed multiple lesions in the right frontal, bilateral occipital and left parietal lobes. EEG demonstrated that ictal discharge was preceded by spike on the right frontal region and FDG-PET showed hypometabolic area in the right frontal lobe. Chronic subdural electrode recordings from the right frontal lobe indicated that ictal onset zone was located around the right frontal lesion, especially frontal tip and base, and these areas including the lesion were resected. Postoperatively, residual seizure was noted although seizure frequency was decreased. It is well known that, postoperatively, satisfactory seizure outcome can be obtained in patients with FCD. However, further investigation in terms of surgical indication and strategies for multiple FCD should be needed.

Tumour necrosis factor-alpha causes an increase in blood-brain barrier permeability during sepsis

Blood-brain barrier (BBB) permeability during sepsis with Escherichia coli or Streptococcus pneumoniae was examined in a mouse model and measured by a circulating beta-galactosidase tracer. The leakage of brain microvascular vessels during sepsis was confirmed by transmission electron microscopic examination of brain tissues stained with horseradish peroxidase. The increase of BBB permeability induced by E. coli and S. pneumoniae, which was maximal at 3 h and 12 h after injection, respectively, was transient because of rapid clearance of the bacteria from the blood. Tumour necrosis factor-alpha (TNF-alpha) was stained on microvascular vessels of the brain during sepsis and intravenous injection of recombinant TNF-alpha also increased the BBB permeability. The increase in BBB permeability induced by either E. coli or S. pneumoniae could be inhibited by anti-TNF-alpha antibody. It was concluded that circulating TNF-alpha generated during sepsis induced the increase in BBB permeability.

A novel platelet-rich arterial thrombosis model in rabbits. Simple, reproducible, and dynamic real-time measurement by using double-opposing inverted-sutures model

Though numerous animal thrombosis models have been introduced, an easy, reliable, and reproducible arterial thrombosis model remains a continuing challenge prior to a thrombolytic study. In an effort to evaluate the efficiency of various recombinant thrombolytic agents with specific affinity to activated platelets in vivo, we developed a novel double-opposing inverted-sutures model to create a platelet-rich thrombus in the femoral artery of rabbits. The arteriotomy was done semicircumferentially, and variously sized microsurgical sutures were introduced intraluminally in a double-opposing inverted manner. The animals were divided into three groups according to the double-opposing inverted-sutures used: Group 1 with 10-0 nylon (n=6), Group 2 with 9-0 nylon (n=6), and Group 3 with 8-0 nylon (n=22). The superficial epigastric branch was cannulated with a thin polyethylene (PE) tube for intraarterial administration of the studied thrombolytic agent. The blood flow was continuously measured with a real-time ultrasonic flow meter. Within 2 h of installation of the sutures, there was no thrombus formation in either Group 1 or 2. In Group 3, the thrombosis rate was 91% (20 of 22) under a steady baseline flow (with an average of 12.23+/-2.40 ml/min). It was highly statistically significant with a P-value of .0000743 using Fisher's Exact Test. The averaged time to thrombosis was 21.8+/-9.8 min. The ultrasonic flow meter to record the dynamic real-time measurement of blood flow was a guideline for thrombus formation or dissolution, which was correlated with the morphological findings of stenotic status of the vessel detected by the Doppler sonography. The components of the thrombus were proven to be platelet-rich predominant by histological examination via hematoxylin and eosin (H&E) stain and transmission electron microscopy (TEM). To confirm that the double-opposing inverted-sutures model would be useful for a study of thrombolytic agents, we evaluated the effects of recombinant tissue-type plasminogen activator (rt-PA) and streptokinase-human plasminogen (SK-HPlg). The average time to thrombolysis post rt-PA infusion was 16.0+/-8.2 min and that of SK-HPlg was 79.6+/-23.1, which were similar to the previous reports. In conclusion, the novel double-opposing inverted-sutures (8-0 nylon) model provides a simple, reliable, and reproducible platelet-rich arterial thrombosis model with noninvasive and dynamic real-time measurement. It may be applied in assessing the efficiency of the recombinant thrombolytic agents and offers many advantages of an arterial platelet-rich in vivo thrombosis model.

Efficacy of single-bolus vs. frequent low-dose treatment with nitrosourea in experimental gliomas

BACKGROUND

Malignant glioma remains a fatal disease. Continuous or frequent low-dose (FLD) chemotherapy with nitrosoureas reportedly causes fewer side-effects than single-bolus therapy without decreasing the antitumour effects.

MATERIALS AND METHODS

To study the effect of FLD treatment with nimustine (ACNU) in rats with glioma, we intracerebrally inoculated with C6 glioma cells. We began the ACNU treatment 5 or 8 days later (total dose, 25 or 40 mg/kg) i.p. as either one bolus or smaller doses spread over 5 days week.

RESULTS

At a total dose of 25 mg/kg beginning at day 8, survival duration did not differ between untreated controls and the FLD group, while the bolus significantly prolonged survival; the FLD group showed some improvement beyond control survival at 40 mg/kg (each p <0.001). Beginning treatment after 5 rather than 8 days prolonged survival somewhat further.

CONCLUSION

FLD treatment with ACNU is less effective against experimental glioma in rats than bolus treatment.

Computerized medical records in the Department of Veterans Affairs

The VA Medical Center in Washington, DC, was the nexus for a number of computerization projects that were initiated by the Department of Veterans Affairs. The culmination of these initiatives is a software package that presents the complete electronic patient record in an easy-to-use graphic user interface. This record combines text data from the legacy data base, diagnostic images from patient procedures, electrocardiograms from a commercial server, an Internet connection, and a hospital web site with pertinent reference information. The information is available in over 1000 places in the hospital and can be accessed remotely using a remote access server. The computerization of the medical record has improved hospital efficiency, has made physician access to patient information more reliable, has opened new opportunities for patient education, and has given healthcare providers more time to care for patients.

Human progesterone receptor shows differential sensitivity to carboxyl group modifying agents when bound to agonist and antagonist ligands

BACKGROUND

Modulation of human uterine progesterone receptor (PR) in relation to its binding to synthetic steroids with known agonist (R5020) and antagonist (triamcinolone acetonide, T.A.) properties was studied in the presence of the specific carboxyl group modifiers, N,N'-dicyclohexylcarbodiimide (DCCD) and 1-ethyl-3-carbodiimide hydrochloride (EDC).

METHODS

Uterine cytosol was treated with DCCD or EDC. The amounts of total bound were detected using the steroid binding measurements. The formation and transformation of progesterone-receptor complexes (PRc) were analyzed using sedimentation rate analysis.

RESULTS

Our studies show that the modification of the COOH group differentially influences the properties of mammalian PR binding with either R5020 or T.A. DCCD and EDC affect the steroid binding of PR by decreasing the binding sites, not by the changing the affinity.

CONCLUSION

Our studies indicate the importance of the carboxyl group in steroid binding by PR. This implies that both aspartic acid and glutamic acid residues, which have the carboxyl group, may play an important role when PR binds with steroid ligands.

Volatile compounds produced from monosodium glutamate in common food cooking

A mixture of soybean oil and/or water, sugar and/or monosodium glutamate (MSG) was water-boiled or oil-heated at 100, 120, 140, 160, or 170 degrees C, respectively, and volatile compounds produced were isolated by solid-phase microextraction and then identified by GC and GC/MS. Oxidative thermal degradation products of fatty acids (OTDPFA) were the major volatile compounds detected for all water-boiled samples. When MSG and sugar were heated together, 2, 5-dimethyl pyrazine and methyl pyrazine were also detected at or after 160 min heating. Water added in soybean oil increased OTDPFA production. In oil-heated samples of soybean oil alone, soybean oil with MSG, and soybean oil with sugar, OTDPFA were also the major compounds found. The samples containing MSG also produced 2-pyrrolidone, and the samples containing sugar also produced furfural and 5-hydroxy methyl furfural. The samples containing soybean oil, sugar, and MSG produced 23 pyrazines, OTDPFA, and gamma-butyrolactone as the major volatile compounds. The contents of OTDPFA were lower in MSG plus sugar and MSG-added samples, and it is postulated that antioxidant activities were produced in cooking.

Heterodyne interferometer with subatomic periodic nonlinearity

A new, to our knowledge, heterodyne interferometer for differential displacement measurements is presented. It is, in principle, free of periodic nonlinearity. A pair of spatially separated light beams with different frequencies is produced by two acousto-optic modulators, avoiding the main source of periodic nonlinearity in traditional heterodyne interferometers that are based on a Zeeman split laser. In addition, laser beams of the same frequency are used in the measurement and the reference arms, giving the interferometer theoretically perfect immunity from common-mode displacement. We experimentally demonstrated a residual level of periodic nonlinearity of less than 20 pm in amplitude. The remaining periodic error is attributed to unbalanced ghost reflections that drift slowly with time.

[Utilizing the PRECEDE model to predict health examination behavior of the elderly]

Health examination of the elderly in Taiwan, the reported rates of health examination of the elderly were always below 30%. In order to explore the predictors related to the behavior of health examination of the elderly, the PRECEDE model was adopted for this study. Both the 1200 participants and spare samples were recruited from eleven districts of Kaohsiung city. 1193 participants had been completed by home interview. Sample size was based on the distribution of the elderly in the whole city and the stratified sampling method was applied. There was no significant difference after comparing the rates of gender, age, and examination between sample and population. The results showed that seven factors could be used to predict the behavior of health examination of the elderly. In the individual predisposing factors, "numbers of chronic diseases", "knowledge of health examination", "previous health examination", and "health promotion behavior" were related to the behavior of health examination of the elderly. In reinforcing factors, "attitude of family members for health examination", and in enabling factors "the guide and the convenience of health-examined services" also showed significantly affecting examination behavior. Therefore, referring to the improvement to be the examination rate, we can intervene or do something through academic, practical and administrative approaches.

Optimal control of blood pressure can reverse left ventricular hypertrophy in uremic hypertensive hemodialysis patients

We investigated the effects of antihypertensive treatment on left ventricular hypertrophy (LVH) of long-term hemodialysis patients. In uremic patients, it is still controversial in antihypertensive effect to the regression of LVH. The left ventricular size and function of 39 uremic hypertensive long-term hemodialysis patients (27 men, 12 women, mean age 58.3) was evaluated with M-mode, 2-dimensional and Doppler echocardiography before, and 12 months after, the start of combined antihypertensive therapy. This therapy included angiotensin II converting enzyme inhibitors, beta-blockers and calcium antagonists. Patients were classified as responders or nonresponders, depending upon whether their systolic blood pressure (SBP) decreased by more than 10 mmHg after antihypertensive treatment for 12 months. Before treatment, 36 (92%) patients had LVH and diastolic dysfunction and three (8%) had systolic dysfunction. At the end of 12 months, only 25 (64%) patients had LVH, 30 (77%) had diastolic dysfunction and 2 (5%) had systolic dysfunction. Left ventricular mass index (LVMI) also decreased from 203.63 +/- 70.47 g/m2 to 178.57 +/- 67.31 g/m2. LVMI correlated with systolic blood pressure (SBP) but did not correlate with diastolic blood pressure (DBP). There were 26 responders and 13 non-responders. Among responders, both the SBP (153.91 +/- 13.24 mmHg vs 134.43 +/- 14.21 mmHg, p < 0.01) and DBP (90.39 +/- 7.89 mmHg vs 79.98 +/- 7.35 mmHg, p < 0.01) decreased significantly after antihypertensive therapy. Responders also exhibited progressive regression of LVH (LVMI decreased significantly from 208.52 +/- 72.03 g/m2 to 168.52 +/- 55.53 g/m2, p < 0.05). However, LVH regression was not found in nonresponders (LVMI showed 194.84 +/- 64.36 g/m2 vs 193.66 +/- 77.67 g/m2). We conclude that good control of blood pressure can reverse LVH in hypertensive hemodialysis patients.

Serous cystic neoplasm involving the pancreas and liver: an unusual clinical entity

Serous cystic neoplasm of the pancreas is typically considered to represent a benign pancreatic neoplasm. We present a case where the tumor displayed unusually aggressive behavior with metastatic disease to the liver and pancreatic bed. Although serous cystic neoplasms should be considered a benign lesion and will be cured in most cases by surgical excision, the radiologist should be aware that on occasion they can exhibit aggressive behavior.

Analytical modeling of the periodic nonlinearity in heterodyne interferometry

The periodic nonlinearity that arises from nonideal laser sources and imperfections of optical components limits the accuracy of displacement measurements in heterodyne interferometry at the nanometer level. An analytical approach to investigating the nonlinearity is presented. Frequency mixing, polarization mixing, polarization-frequency mixing, and ghost reflections are all included in this investigation. A general form for the measurement signal, including that of the distortions, is given. The analytical approach is also applicable to homodyne interferometry.

Breast carcinoma metastatic to the esophagus. CT findings with pathologic correlation

The common sites of metastasis from breast carcinoma include local and distant lymph nodes, lung parenchyma, bone, liver and brain. While less common, gastrointestinal carcinoma, involving everything from the tip of the tongue to the rectum, secondary to metastatic breast carcinoma have been reported. Many of these lesions occur years after treatment of the primary breast cancer and they can be confused with a second primary. We present a case of breast cancer metastatic to the esophagus which produced symptoms of progressive dysphagia in a women thirteen years after mastectomy and radiation therapy for breast cancer.