Low-dose imiquimod induces melanogenesis in melanoma cells through an ROS-mediated pathway

BACKGROUND

Melanogenesis is the process of melanin maturation which not only protects skin from UV radiation but also plays an important role in antigenicity of melanomas. Imiquimod (IMQ) is a toll-like receptor 7 (TLR7) agonist that exhibits antiviral and anticancer activity.

OBJECTIVE

To explore whether IMQ could induce melanogenesis in melanoma cells.

METHODS

The mouse melanoma cell line B16F10, the mouse immortalized melanocyte Melan-A, and human melanoma cell lines MNT-1, C32 and A375 were utilized in this study. The pigmented level was observed by the centrifuged cell pellet. The intracellular and extracellular melanin levels were examined in the absorbance in NaOH-extracted cell lysate and cell-cultured medium, respectively. The expression of melanogenesis related proteins was examined by immunoblotting. The intracellular cyclic AMP amount was evaluated by the cAMP Glo assay kit. The activity of phosphodiesterase 4B (PDE4B) was investigated by CREB reporter assay with overexpressed PDE4B or not.

RESULTS

We demonstrated that a low dose of IMQ could trigger melanogenesis in B16F10 cells. IMQ induced microphthalmia-associated transcription factor (MITF) nuclear translocation, upregulated the expression of melanogenesis-related proteins, increased tyrosinase (TYR) activity, and led to pigmentation in B16F10 cells. Next, we found that IMQ-induced melanogenesis was activated by excessive intracellular cAMP accumulation, which was regulated through IMQ-mediated PDE4B inhibition. Finally, IMQ-induced ROS production was found to be involved in melanogenesis by its control of PDE4B activity.

CONCLUSIONS

Low dose of IMQ could activate melanogenesis through the ROS/PDE4B/PKA pathway in melanoma cells.

Heat shock protein 70 protects the lungs from hyperoxic injury in a neonatal rat model of bronchopulmonary dysplasia

Hyperoxia plays a significant role in the pathogenesis of lung injury, such as bronchopulmonary dysplasia (BPD), in premature infants or newborns. BPD management aims to minimize further injury, provide an optimal environment to support growth and recovery. In clinic neonatal care, we need a new therapy for BPD. Heat shock protein 70 (Hsp70) inhibit cell apoptosis and promote cell repair allowing cells to survive lethal injury. We hypothesized that Hsp70 could be used to prevent hyperoxia related BPD in the neonatal rat model through its anti-apoptotic and anti-inflammatory effects. In this study, we explored the effect of Hsp70 on hyperoxia-induced lung injury using neonatal rats. Neonatal Wistar rats were delivered naturally at full term of gestation and were then pooled and randomly assigned to several groups to receive heat stimulation (41°C for 20 min) or room temperature conditions. The Hsp70 group received recombinant Hsp70 intraperitoneally (200 μg/kg, daily). All newborn rats were placed under hyperoxic conditions (85% oxygen) for 21 days. Survival rates in both heat-hyperoxia and Hsp70-hyperoxia groups were higher than those in the hyperoxia group (p < 0.05). Both endogenous and exogenous Hsp70 could reduce early apoptosis of alveolar cells under hyperoxia. Additionally, there were less macrophage infiltration in the lung of the Hsp70 groups (p < 0.05). Heat stress, heat shock proteins, and exogenous recombinant Hsp70 significantly increased the survival rate and reduced pathological hyperoxia induced lung injuries in the development of BPD. These results suggest that treating hyperoxia-induced lung injury with Hsp70 may reduce the risk of developing BPD.

Imiquimod-induced ROS production causes lysosomal membrane permeabilization and activates caspase-8-mediated apoptosis in skin cancer cells

BACKGROUND

Lysosomal cell death is induced by lysosomal membrane permeabilization (LMP) and the subsequent release of lysosomal proteolytic enzymes, including cathepsins (CTSs), which results in mitochondrial dysfunction and apoptosis. Imiquimod (IMQ), a synthetic TLR7 ligand, has both antiviral and antitumor activity against various skin malignancies in clinical treatment. Previously, we demonstrated IMQ not only caused lysosomal dysfunction but also triggered lysosome biogenesis to achieve lysosomal adaptation in cancer cells.

OBJECTIVE

To determine whether lysosomes are involved in IMQ-induced apoptosis.

METHODS

The human skin cancer cell lines BCC, A375 and mouse melanoma cell line B16F10 were used in all experiments. Cell death was determined by the Cell Counting Kit-8 (CCK-8) assay and DNA content assay. Protein expression was determined by immunoblotting. Caspase-8 activity was assessed using a fluorescence caspase-8 kit and determined by flow cytometry and confocal microscopy.

RESULTS

IMQ not only induced lysosome damage but also abrogated lysosome function in skin cancer cells. IMQ-induced caspase-8 activation contributed to the processes of lysosomal cell death. Moreover, the use of ROS scavengers significantly abolished caspase-8 activation and inhibited IMQ-induced LMP. Additionally, pharmacological inhibition of CTSD not only abrogated caspase-8 activation but also rescued IMQ-induced cell death. Finally, lysosome-alkalizing agents enhanced the cytotoxicity of IMQ in vitro and in vivo.

CONCLUSIONS

IMQ-induced ROS accumulation promotes LMP, releases CTSs into the cytosol, stimulates caspase-8 activation and finally causes lysosomal cell death. Lysosomal cell death and the CTSD/caspase-8 axis may play a crucial role in IMQ-induced cell death.

Using a neonatal rat model to explore the therapeutic potential of coenzyme Q10 in prematurity under hyperoxia

Hyperoxia, is often used in preterm supportive care, leading to high oxygen exposure in neonates. Coenzyme Q10 (CoQ10) is a free radical scavenger that has been studied in older children but never be investigated for its role in preterm care. We hypothesize that the administration of exogenous CoQ10 would raise serum concentrations of CoQ10 and mitigate the adverse effects of hyperoxia on the organs by reducing oxygen-free radicals and inflammation. The aim of this study was to evaluate the effects of oxidative stress, inflammatory response, and survival in neonatal rats after CoQ10 treatment. Neonatal rats delivered from four pregnant Wistar rats were randomly divided into four groups: (a) control, (b) CoQ10, (c) hyperoxia (O₂ group), and (d) treatment (CoQ10 + O₂ ) groups. The dose of CoQ10 injected was 30 mg/kg. The CoQ9, CoQ10, cytokines, oxidative stress, and antioxidant enzyme activity were measured. Tissue samples were histologically examined and mortality was monitored for 16 days. The level of CoQ9 significantly increased in the liver, kidney, and plasma, while the level of CoQ10 significantly increased in most organ tissues in the CoQ10 + O₂ group. Additionally, CoQ10 decrease oxidative stress in the liver, increase antioxidant enzyme activity in the heart, kidney, and brain, and reverse an inclined level of hematopoietic growth factors. However, CoQ10 had no effect on inflammation, organ damage, or mortality. Therefore, the use of CoQ10 in potential adjuvant therapy for neonatal hyperoxia requires further research.

Synergistic Anticancer Effects of Gemcitabine with Pitavastatin on Pancreatic Cancer Cell Line MIA PaCa-2 in vitro and in vivo

Background

Pancreatic ductal adenocarcinoma (PDAC) is a highly aggressive malignancy with an overall 5-year survival rate of 9.3%, and this malignancy is expected to become the second leading cause of cancer-related death by 2030. Gemcitabine resistance develops within weeks of PDAC patient’s chemotherapeutic initiation. Statins, including pitavastatin, have been indicated to have anticancer effects in numerous human cancer cell lines. Thus, in this study, we hypothesized that a combination of gemcitabine and pitavastatin may have a greater anticancer effect than gemcitabine alone on the human pancreatic carcinoma cell line MIA PaCa-2.

Methods

The anticancer effects of gemcitabine with pitavastatin were evaluated using human MIA PaCa-2 cell line in vitro and in vivo Balb/c murine xenograft tumor model. Cell viability was assessed with CCK-8, and cell migration was stained by crystal violet. Cell cycle distribution, apoptosis and mitochondrial membrane potential were examined by flow cytometry. Activation of drug transporters (hENTs, hCNTs), intracellular drug activating (dCK) and inhibition of inactivating enzymes (RRMs) pathways were assessed by Western blotting analysis. Molecular mechanisms and signaling pathways of apoptosis, necrosis and autophagy also were assessed by Western blotting.

Results

We observed that gemcitabine and pitavastatin synergistically suppressed the proliferation of MIA PaCa-2 cells through causing sub-G1 and S phase cell cycle arrest. Activation of apoptosis/necrosis was confirmed by annexin V/propidium iodide double staining, which showed increasing levels of active caspase 3, cleaved poly(ADP-ribose) polymerase and the RIP1–RIP3–MLKL complex. Moreover, gemcitabine–pitavastatin-mediated S phase arrest downregulated cyclin A2/CDK2 and upregulated p21/p27 in MIA PaCa-2 cells. Furthermore, this combination improved drug cellular metabolism pathway, mitochondria function and activated autophagy as part of the cell death mechanism. In vivo, gemcitabine-pitavastatin effectively inhibited tumor growth in a nude mouse mode of Mia PaCa-2 xenografts without observed adverse effect.

Conclusion

Combined gemcitabine–pitavastatin may be an effective novel treatment option for pancreatic cancer.

Subcutaneous injection of recombinant heat shock protein 70 ameliorates atopic dermatitis skin lesions in a mouse model

Atopic dermatitis (AD) is a chronic inflammatory skin disease and sometimes is a tough challenge for physicians. We previously reported that in Th2 environment, the production and secretion of thymic stromal lymphopoietin (TSLP) from human keratinocytes was inhibited by recombinant heat shock protein 70 (rHSP70). The present study assessed the therapeutic effectiveness of rHSP70 in a mouse model of AD. An experimental model of AD was reproduced by systemic sensitization and local epicutaneous challenge with ovalbumin (OVA). Treatment of rHSP70 was performed by subcutaneous administration. The levels of OVA-specific IgE, as well as cytokines, were detected by ELISA. Skin samples from patch areas were also taken for histologic examination. Injection of rHSP70 improved the histologic picture by reducing the thickness of epidermis and allergic inflammation. Skin sonography revealed rHSP70 ameliorated skin remodeling. rHSP70 also significantly decreased the protein expression of TSLP of skin from patch areas. Furthermore, in ex vivo studies also showed group of rHSP70 treatment decreased IL-13, RANTES, MIP-1β and increased IFN-γ secreted from splenocytes stimulated with OVA. The rHSP70 intervention in the mouse model of AD reduced the skin expression of TSLP and attenuated the clinical appearance of OVA-induced AD mice. The effect was achieved by suppressed Th2 immune response in injected skin tissue and enhanced systemic Th1 immune response. These results suggest that rHSP70 have potential as a promising protein for the treatment of AD.

Risk score algorithm for treatment of persistent apical periodontitis

Persistent apical periodontitis related to a nonvital tooth that does not resolve following root canal treatment may be compatible with health and may not require further intervention. This research aimed to develop a Deterioration Risk Score (DRS) to differentiate lesions requiring further intervention from lesions likely to be compatible with health. In this cross-sectional study, patient records (2003-2008) were screened for root-filled teeth with periapical radiolucency visible on periapical radiographs taken at treatment and at recruitment at least 4 yr later. The final sample consisted of 228 lesions in 182 patients. Potential demographic and treatment risk factors were screened against 3 categorical outcomes (improved/unchanged/deteriorated), and a multivariate independent multinomial probit regression model was built. A 5-level DRS was constructed by summing values of adjusted regression coefficients in the model, based on predicted probabilities of deterioration. Most lesions (127, 55.7%) had improved over time, while 32 (14.0%) remained unchanged, and 69 (30.3%) had deteriorated. Significant predictors of deterioration were as follows: time since treatment (relative risk [RR]: 1.11, 95% confidence interval [CI]: 1.01-1.22, p = .030, rounded beta value = 1, for every year increase after 4 yr), current pain (RR: 3.79, 95% CI: 1.48-9.70, p = .005, rounded beta value = 13), sinus tract present (RR: 4.13, 95% CI: 1.11-15.29, p = .034, rounded beta value = 14), and lesion size (RR: 7.20, 95% CI: 3.70-14.02, p < .001, rounded beta value = 20). Persistent apical periodontitis with DRS <15 represented very low risk; 15-20, low risk; 21-30, moderate risk; 31-40, high risk; and >40, very high risk. DRS could help the clinician identify persistent apical periodontitis at low risk for deterioration, and it would not require intervention. When validated, this tool could reduce the risk of overtreatment and contribute toward targeted care and better efficiency in the timely management of disease.

Antitumor efficacy and pharmacokinetics of a novel gemcitabine oral formulation (INNO-D07001) in xenograft animal models

e14699

Background: INNO-D07001 is a novel oral gemcitabine formulation which was developed to enhance the oral bioavailability of gemcitabine and it has been successfully demonstrated in both beagle dogs as well as nude mice. The objectives of this study were to examine the antitumor activity of this novel gemcitabine oral formulation in human xenograft models of pancreatic tumors with different daily doses as well as various dosing schedules. Methods: The INNO-D07001 dosing solutions (gemcitabine oral formulation) were formulated freshly before treatment and water for injection (USP) was used as the diluent. There were seven groups in the study and it was ten female NCr-nu/nu mice (with human CFPAC-1 pancreatic tumor) per group. Two doses (5 mg/kg and 10 mg/kg) and three dosing schedules (Q1D, Q2D, and Q3D) were examined. Water for injection (by oral administration) was used as the blank control and Gemzar (180 mg/kg by I.V.) was used as the active control. All INNO-D07001 dosing solutions were administered to mice by P.O. and, on the other hand, Gemzar was administered to mice by I.V. All animals were designed to receive doses for 12 days based on different doses and dosing schedules. Total body weights and tumor sizes were recorded continuously for evaluating the toxicity and antitumor activity, respectively, of INNO-D07001. Results: Oral administration of INNO-D07001 once daily at doses of 10 and 5 mg/kg/dose was not tolerated. In contrast, oral administration of INNO-D07001 on a Q2Dx6 schedule at a dose of 10 mg/kg/dose and on a Q3Dx4 schedule at doses of 10 and 5 mg/kg/dose was well tolerated. Moreover, the INNO-D07001 treatment at a dose of 10 mg/kg/dose on a Q2Dx6 schedule produced statistically significant inhibition of tumor growth (i.e. more than 60% inhibition rate comparing to the blank control) on the last treatment day. Conclusions: The novel gemcitabine oral formulation (INNO-D07001) is well tolerated and effective at a dose of 10 mg/kg/dose on a Q2Dx6 schedule to show the significant inhibition of pancreatic tumor growth. Future preclinical study in toxicity evaluation with repeating doses is ongoing in order to provide adequate safety information before entering phase I clinical study.

Surface-surface interaction in smectic liquid crystal films

Null transmission ellipsometry was employed to study the field induced transition of the surface arrangements in freestanding films of smectic liquid crystals. The interlayer interaction between the two surfaces obtained from the threshold voltage for the transition is found to be antiferroelectric and is quasilong ranged. The possible microscopic origins of the measured interaction and its relevance to the interlayer interaction in antiferroelectric liquid crystal materials are discussed.

Synthesis of ethanol-soluble few-layer graphene nanosheets for flexible and transparent conducting composite films

We report a facile method of preparing few-layer graphene nanosheets (FLGs), which can be soluble in ethanol. Atomic force microscopy and high-resolution transmission electron microscopy studies reveal that FLGs have average thicknesses in the range of 2.6-2.8 nm, corresponding to 8-9 layers. A graphene/nafion composite film has a sheet resistance of 9.70 kΩ/sq at the transmittance of 74.5% (at 550 nm) while the nafion film on polyethylene terephthalate has a sheet resistance of 128 kΩ/sq at transmittance of 90.0%. For the cycling/bending test, almost no change in resistance was exhibited when the film was bent at an angle up to 140°, and no obvious deviation in resistance could be found after 100 bending cycles was applied. In addition, an FLGs-poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) composite layer was demonstrated as the effective hole transporting layer to improve the hole transporting ability in an organic photovoltaic device, with which the power conversion efficiency was enhanced from 3.10% to 3.70%. The results demonstrated the promising applications of FLGs on graphene-based electronics, such as transparent electrode and flexible conducting film.

Thickness dependent phase behavior of antiferroelectric liquid crystal films

Free standing films of a liquid crystal compound with simple surface enhanced order were studied. The resultant phase diagram demonstrates that (1) the short helical pitch smectic-C(alpha)* phase disappears below a film thickness of 10 layers, and (2) the temperature window of a distorted 4 layer smectic-C(FI2)* phase increases dramatically upon decreasing film thickness. The experimental findings were attributed to the reduced dimensionality and enhanced surface effects in thin films. The results of the smectic-C(alpha)* phase are consistent with what have been reported for helically ordered magnetic thin films, with a noticeable difference due to the opposite effect of the surface on ordering in the two systems.

Surface-induced ordering effect in one antiferroelectric liquid crystal compound

Null transmission ellipsometer was employed to study the surface-induced tilt transition of an antiferroelectric liquid crystal compound in the bulk smectic- A (SmA) temperature range. The data of the surface tilt transition can be fitted with an extended mean-field model. These results indicate the transition is near a mean-field tricritical point. The surface layers' tilt directions are found to be in different planes several degrees above the bulk SmA-SmC_{alpha};{ *} transition.

Ageing and infection

An increased morbidity and mortality due to infectious disease has been noted in the ageing. Two alternative explanations may account for this. Changes in the immune system and inflammatory responses with age or an increase in age-related diseases may underlie the increased susceptibility. A review of studies of healthy older individuals demonstrates changes in the immune system with ageing but minimal change in the inflammatory response. Investigations of severe infection in older nursing-home patients requiring hospitalization indicate that infection as a cause of admission and death is significantly more common in individuals who are bedridden because of serious cardiovascular or neurological disease and require urinary catheterization. The evidence indicates that underlying disease, not the senescence of host resistance, leads to severe infection in the ageing.

Unique pitch evolution in the smectic-C+alpha phase

Employing resonant x-ray diffraction, we observed unique pitch evolutions in the smectic-C*(alpha) phase in mixtures of two antiferroelectric liquid crystals. Our results show that the pitch in this phase continuously evolves across 4 layers, contradicting a theoretical model that predicts that the smectic-C*(FI2) phase intervenes in the smectic-C*(alpha) phase. The phase sequences we found can be explained by another model that includes one type of long-range interaction among smectic layers.

Effect of enantiomeric excess on surface structures and phase sequences in free-standing liquid-crystal films

We present differential optical reflectivity and null transmission ellipsometry data from several mixtures of MHPBC enantiomers. From this data, we have determined the chiral smectic phase sequence as a function of enantiomeric excess. The data suggest a change in the structure of the smectic-C(*)(alpha) phase and the surface tilt state as the enantiomeric excess is reduced. The results also show that the intermediate phases, smectic C(*)(FI2), smectic C(*)(FI1), and smectic C(*)(alpha), disappear sequentially on reducing the net chirality.

Sacral parasite conjoined twin

BACKGROUND

A variant of conjoined twins is one in which one twin is incomplete.

CASE

A female infant was born vaginally at 40 weeks' gestation to a healthy primipara. No important abnormalities were noted during prenatal examinations. The infant was fully developed in all external aspects except for a parasitic body conjoined with her sacrococcygeal region. Separated by operation 2 weeks after birth, the parasite contained lower limbs, adipose tissue, muscles, and a bowel sac. Over 4 years of observation, no abnormalities have been found since the operation.

CONCLUSION

Obstetricians should be aware of the existence of a parasite twin during prenatal examinations and of the importance of the differential diagnosis of parasite and teratoma, a neoplasm with malignant potential.

Heterotrimeric G-protein and signal transduction in the nematode-trapping fungus Arthrobotrys dactyloides

The fungus Arthrobotrys dactyloides produces specialized constricting rings to trap and then consume nematodes. The signal transduction pathway involved in the nematode-trapping process was examined. Mastoparan, an activator of G-protein, had a stimulatory effect on the inflation of ring cells, whereas a G-protein inhibitor, pertussis toxin, prevented ring-cell expansion. The 40-kDa G alpha of heterotrimeric G-proteins was specifically ADP-ribosylated by pertussis toxin. Using an antibody specific to the 35-kDa subunit G beta, we showed that immunogold-labeled G beta was more concentrated in ring cells than in the hyphae. In the absence of nematodes, the rings could be inflated by either pressurizing the culture in a syringe, raising intracellular Ca2+ concentrations, or adding warm water. We used these methods to reveal differences in responses to antagonists. The results support a model in which the pressure exerted by a nematode on the ring activates G-proteins in the ring cells. The activation leads to an increase in cytoplasmic Ca2+, activation of calmodulin, and finally the opening of water channels. The ring cells expand to constrict the ring and thus immobilize the nematode.

Soy isoflavone supplementation in postmenopausal women. Effects on plasma lipids, antioxidant enzyme activities and bone density

OBJECTIVE

To investigate isoflavone supplementation on plasma lipids, erythrocyte antioxidant enzyme activities and bone mineral density in postmenopausal women.

STUDY DESIGN

Thirty-seven postmenopausal women were given 150 mg/d of isoflavone supplements twice daily for six months. Blood was sampled before and after supplementation, at three and six months.

RESULTS

There were no significant differences in plasma total cholesterol, high-density lipoprotein cholesterol, low-density lipoprotein cholesterol, triglyceride concentrations or erythrocyte antioxidant enzyme activities after three and six months of supplementation when compared with the baseline. No significant changes were noted in calcaneus bone mineral density after supplementing isoflavones for six months.

CONCLUSION

The antioxidant effect of isoflavones in normal postmenopausal women is not obvious, and supplementation with isoflavone alone may not have a hypocholesterolemic effect. Since the duration of this study was too short with respect to bone density, longer studies are needed to clarify the bone-sparing effect of isoflavone supplementation.

Mutational analysis of the Arabidopsis RPS2 disease resistance gene and the corresponding pseudomonas syringae avrRpt2 avirulence gene

Plants have evolved a large number of disease resistance genes that encode proteins containing conserved structural motifs that function to recognize pathogen signals and to initiate defense responses. The Arabidopsis RPS2 gene encodes a protein representative of the nucleotide-binding site-leucine-rich repeat (NBS-LRR) class of plant resistance proteins. RPS2 specifically recognizes Pseudomonas syringae pv. tomato strains expressing the avrRpt2 gene and initiates defense responses to bacteria carrying avrRpt2, including a hypersensitive cell death response (HR). We present an in planta mutagenesis experiment that resulted in the isolation of a series of rps2 and avrRpt2 alleles that disrupt the RPS2-avrRpt2 gene-for-gene interaction. Seven novel avrRpt2 alleles incapable of eliciting an RPS2-dependent HR all encode proteins with lesions in the C-terminal portion of AvrRpt2 previously shown to be sufficient for RPS2 recognition. Ten novel rps2 alleles were characterized with mutations in the NBS and the LRR. Several of these alleles code for point mutations in motifs that are conserved among NBS-LRR resistance genes, including the third LRR, which suggests the importance of these motifs for resistance gene function.

Temporary hearing impairment after general anesthesia--a case report

The incidence of hearing impairment after anesthesia is rare. We report a case who received left total knee and hip replacement and developed severe hearing impairment of the left ear after general anesthesia. Examination of the left ear by an otolaryngologist showed that there was no noticeable abnormality. The hearing acuity recovered gradually and returned to normal 3 days later. The use of nitrous oxide during anesthesia was incriminated as the possible cause.

Low dose ketamine and midazolam as supplements for spinal anesthesia

BACKGROUND

Low dose ketamine and midazolam together were used as supplements during spinal anesthesia to provide analgesia for insertion of spinal needle and intraoperative sedation.

METHODS

Two regimens of drug combination (ketamine 0.5 mg/kg and midazolam 0.05 mg/kg in group I, n = 30; ketamine 0.5 mg/kg and midazolam 0.1 mg/kg in group II, n = 30) were administered intravenously before proceeding lumbar puncture.

RESULTS

Systolic and diastolic arterial blood pressure, heart rate, and arterial oxygen saturation did not change significantly before and after the administration of drugs. Most patients in both groups showed good analgesic response to the lumbar puncture. The medications induced a brief unconsciousness (4.1 min in group I; 8.5 min in group II). The time from drug administration to recovery of mental orientation was 8.8 min in group I and 15.1 min in group II. The regimens also provided intraoperative sedation. Patients in group II appeared to be more depressed than group I in the first 30 min. None of the patients had significant respiratory disturbance, involuntary movement, or recall to spinal puncture. There were 7 patients in group I and 4 patients in group II who experienced dreaming.

CONCLUSIONS

The use of low dose ketamine together with midazolam as supplement for spinal anesthesia is helpful in anesthetic practice.

[The role of nurse anesthetist in Taiwan (questionnaire report)]

BACKGROUND

Anesthesia as a specialty was introduced to Taiwan for over 40 years. In early days, there were quite a number of nurse anesthetists who were trained to share the heavy burden of anesthetic work. However, due to the increasing demand for better anesthetic quality, the role of nurse anesthetists is open to discussion.

METHODS

Questionnaires were sent to anesthesiologists working in medical centers, regional hospitals, and district hospitals. We hoped to find out the present working condition of nurse anesthetists and what their future role would be.

RESULTS

Over one-half of the questionnaires collected agree that nurse anesthetists should not conduct anesthesia by their own, and that they should only help prepare patients and drugs for anesthesia.

CONCLUSIONS

Anesthesia as a highly specialized field of medicine should be conducted by qualified and well trained anesthesiologists only. Training for nurse anesthetists should be confined to preparation of drugs and care of patients only.

Polarization-Dependent Periodic Pulse Oscillation in a Diode-Laser-Pumped and Intracavity Frequency-Doubled Nd:YVO 4 Laser

We demonstrate that two cross-polarized longitudinal modes can have 50% higher conversion efficiency than two parallel-polarized longitudinal modes in a diode-laser-pumped and intracavity frequency-doubled Nd:YVO(4) laser when operated under periodic pulse oscillation. Through simulations of the rate equations for primary frequency intensities and gains, we also verify that this effect can be attributed to gain competition and complementary conversion coefficient between second-harmonic and sum-frequency generations.