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.

Effects of various chemical sterilization methods on the crosslinking and enzymatic degradation characteristics of an epoxy-fixed biological tissue

Due to the nature of bioprostheses, which are mainly biological tissues that cannot be sterilized with heat or irradiation, the sterilization method by choice is generally liquid chemicals. It is known that a number of liquid chemicals can have rapid germicidal effect and can be used to sterilize bioprostheses. The study was to evaluate the effects of various chemical sterilization methods on the crosslinking and enzymatic degradation characteristics of an epoxy-fixed biological tissue. The chemical sterilants employed were: a 70% ethanol solution (EtOH), a 2% epoxy compound + 20% ethanol solution (EX-810), a 2% propylene oxide + 20% ethanol solution (PO), and a 0.625% glutaraldehyde + 20% ethanol + 0.2% polysorbate solution (GA). Both masking and crosslinking of the free amino groups within the epoxy-fixed tissue were observed subsequent to sterilization with GA or EX-810. This improved the resistance of the GA or EX-810 sterilized tissues against collagenase degradation as compared to its nonsterilized counterpart. However, subsequent to sterilization with PO, only masking of the free amino groups within the epoxy-fixed tissue was noted. The inhibition of the collagenase degradation by masking of the free amino groups was traded off by the more random molecular packing of the PO sterilized sample due to the introduction of the side branches. Sterilization of the epoxy-fixed tissue with EtOH may increase its denaturation temperature and tensile strength, while neither masking nor crosslinking of free amino groups within the tissue took place. The resistance to degradation of the EtOH sterilized tissue, however, did not improve as compared to its nonsterilized counterpart.

[The shear bond strength of porcelain and base metal alloys for metal-ceramic crown (VII)]

The popularity of the base metal alloys has increased in the past decade because of their lower price, high tensile strength and high elastic modulus. Several factors are critical in ensuring successful bonding: the matching of the thermal coefficients of expansion and constraction of the porcelain and metal, the metallurgic composition of the alloy and the pretreatment procedures used in preparation of the metal substructure. Two ceramic base alloys (one alloy contains beryllium, another without) were studied. The surface textures were created by 50 microns, 100 microns aluminum oxide sandblasting, carbide bur, carborundum point and disk upon two base alloys, Rexillium III and Wiron 88. The purposes of this investigation were to determine how these variations in surface texture affect the bond strength of the two ceramo-metal alloy systems. The following results were obtained: 1. Statistics revealed that bond strength was not significantly increased with surface roughness (p > 0.05). 2. The shear bond strength for variable pretreatment methods were in the following sequence: 100 microns Al2O3 sandblasting, carbide bur, 50 microns Al2O3 sandblasting, carborundum point, disk. 3. The Rexillium III alloy had a significantly higher bond strength than Wiron 88 alloy (p < 0.05). 4. The Noritake porcelain showed a significantly higher bond strength than Biobond porcelain (p < 0.05). 5. The fracture site was cohesive and adhesive mode treated with 50 microns Al2O3, 100 microns Al2O3, carbide bur. But carborundum point and disk was adhesive mode.

[The shear bond strength of porcelain and base metal alloys for metal-ceramic crown (VI)]

The popularity of base metal alloy for porcelain fused to a metal crown and bridges has increased recently because of lower price, superior yield strength and modulus of elasticity (rigidity). The use of these alloys give them the potential advantage of thinner coping with less material and the required rigidity for long-span fixed partial dentures. The addition of beryllium to base metal alloys increases fluidity and improves casting fit. Beryllium also controls surface oxidation and bonding strength. Oxidation heat treatment of the metal is used to remove entrapped air, eliminate organic material and form the metal oxidized layer. The bonding agent and gold bonding agent also affect the bonding strength between porcelain and metal alloys. Four commercially available ceramic base alloys (two alloys contain beryllium element, another two do not) are studied. The purposes of this investigation are to test the shear bond strength between porcelain and metal alloy under different conditions (oxidized layer removed or not, gold bonding agent and uniseal bonding agent used in combination, separately or not at all). The following results were obtained: 1. Whether the oxidized layer was removed or not did not have a significant effect on the bond strength of porcelain (p > 0.05). 2. When different metal alloys was used, Wiron 88 alloy showed significantly the best bond strength of all alloys tested (p < 0.05). 3. When different bonding agent were used, the combination of bonding agent and gold bonding agent showed the best bond strength of all bonding agents tested. It showed a significantly higher bonding strength than opaque layer and gold bonding agent. 4. Vita porcelain powder showed a significantly higher bond strength than did Unibond porcelain (p < 0.05). 5. When opaque layer was used and when no bonding agent was used, the porcelain powder significantly affected the bond strength (p < 0.0001). The Vita porcelain showed a significantly higher bond strength than did Unibond porcelain. Wiron 88 alloy showed significantly the high bond strength than Rexillium III alloy (p < 0.05). 6. When bonding agent was used, the porcelain powder and alloy significantly affected bond strength. The Vita porcelian showed a significantly higher bond strength than did Unibond porcelain. Wiron 88 alloy showed significantly the best bond strength than other alloys Wiron (p < 0.05). 7. When bonding agent and gold bonding agent were used, the porcelain powder significantly affected the bond strength (p < 0.05). The Vita porcelain showed a significantly higher bond strength than did Unibond porcelain (p < 0.05). 8. When gold bonding agent was used, there was not any bond strength between metal and powder.

Dibutyryl cAMP prevents increased vascular permeability caused by air embolism in isolated rat lungs

BACKGROUND AND HYPOTHESIS

Venous gas bubbles are routinely detected in astronauts undergoing extravehicular activities at lower suit pressure. Venous air embolism increases the pulmonary arterial pressure and the vascular permeability leading to acute lung injury. In the present study we evaluated the protective effect of dibutyryl cAMP, aminophylline, and pentoxifylline on the pulmonary vasculatures after air embolism.

METHOD

In isolated and perfused rat lungs, we induced air embolism by introducing air bubbles into the pulmonary artery. We measured the pulmonary arterial pressures and capillary pressure. Vascular permeability was determined by measuring the filtration coefficient (Kf) and the protein concentration in the lung lavage fluid.

RESULTS

Air infusion caused pulmonary hypertension and increased vascular permeability, resulting in pulmonary edema. The Kf (in g.min-1.cm H2O-1.100 g-1) increased from 0.44 +/- 0.05 at baseline to 2.98 +/- 0.47 after air infusion. Pretreatment with DBcAMP prevented the increase in Kf (0.63 +/- 0.09) caused by air embolism without altering the hemodynamics. Aminophylline and pentoxifylline did not prevent lung injury induced by air embolism. Although aminophylline did not alter the response of pulmonary arterial pressure to air infusion, it elevated the capillary pressure to 5.1 +/- 0.4 mmHg, which was significantly greater than that in the lung receiving air infusion alone.

CONCLUSION

Our results suggest that DBcAMP prevents the increase in vascular permeability caused air embolism. The ineffectiveness of aminophylline and pentoxifylline on the prevention of air embolism-induced lung injury remains for further investigation.

Degradation potential of biological tissues fixed with various fixatives: an in vitro study

The purpose of this study was to investigate the in vitro degradation potential of porcine pericardia fixed with various aldehyde or epoxy compound (EC) fixatives, using bacterial collagenase and pronase. The fixatives investigated were formaldehyde (FA), glutaraldehyde (GA), monofunctional EC (EX-131), and multifunctional ECs (EX-810, EX-313, and EX-512). Fresh porcine pericardium was used as a control. The test samples were well immersed in a 20-U/mL collagenase solution or a 10-U/mL pronase solution and incubated at 37 degrees C at pH 7.5 for 24 h. The extent of degradation of each test sample was determined by measuring its increment in free amino group content and changes in collagen structure, denaturation temperature, and tensile stress after degradation. In general, the extent of tissue degradation with pronase was more notable than with collagenase. As observed with fresh tissue, the EX-131 EC fixed tissue radically disintegrated after either collagenase or pronase degradation, whereas the other test samples remained intact. The reason for this may reside in the more random molecular packing of the EX-131 EC-fixed tissue, which led to some loss in its helical integrity. This made penetration of enzymes into biological tissue easier. Of the multifunctional EC test groups, tissues fixed with tetrafunctional EC (EX-521) or trifunctional EC (EX-313) had relatively better resistance to degradation than those fixed with bifunctional EC (EX-810). The extent of degradation for the EX-313 or EX-512 EC fixed tissues was similar to that observed for the FA- or GA-fixed tissues. The results of this study indicated that the biological tissue fixed with monofunctional EC (EX-131) cannot resist bacterial collagenase or pronase degradation. However, resistance to degradation of the multifunctional EC (EX-313 or EX-152)-fixed tissues was comparable to that of the aldehyde (FA or GA)-fixed tissues. Therefore, of various EC fixatives, the EC with a greater number of functional groups should be chosen for tissue fixation to increase its resistance to enzymatic degradation.

Fixation of various porcine arteries with an epoxy compound

The clinical results of biological vascular grafts have been unsatisfactory. The poor results of these vascular grafts may be attributed to the fixatives, aldehydes, used in fixing tissues. In an attempt to overcome this problem, a new fixative, epoxy compound, has recently been used to fix biological vascular grafts. The study was undertaken to investigate the crosslinking characteristics, fixation index and denaturation temperature, of various porcine arteries fixed with an epoxy compound. The porcine arteries investigated in the study were the common carotid artery, internal thoracic artery, abdominal aorta, and saphenous artery. In addition, the effects of sonication on the porcine arteries before fixation on their crosslinking characteristics were analyzed. The fresh and glutaraldehyde-fixed arteries were used as controls. It was noted that glycine, proline, and alanine were the most abundant amino acids found in the porcine internal thoracic artery. In the amino acid analysis, it was observed that the amino acids in the porcine arteries reacted with epoxy compound or glutaraldehyde were lysine, hydroxylysine, histidine, and arginine. Of these amino acids, lysine was the most reactive. In general, the fixed arteries were relatively stiffer than their fresh counterparts. The fixation indices and denaturation temperatures of various porcine arteries were comparable throughout the entire fixation process. The amounts of free amino groups of the sonicated arteries were significantly lower than those of their unsonicated counterparts (p < 0.05). It is speculated that the diminishing free amino groups of the sonicated arteries may be attributed to the removal of the destroyed cell debris and adherent proteins of the arteries after sonication. However, it was learned that sonication on the porcine arteries before fixation did not seem to affect their fixation indices and denaturation temperatures. The results obtained in this study may help one in selecting the raw materials for developing a small-diameter biological vascular graft

Physical properties of a porcine internal thoracic artery fixed with an epoxy compound

This study aimed to investigate the physical properties of a porcine internal thoracic artery fixed with an epoxy compound. Fresh and glutaraldehyde-fixed porcine arteries were used as controls. Both the epoxy-fixed and glutaraldehyde-fixed porcine arteries showed significant increases in fixation index and denaturation temperature as compared to the fresh one. Additionally, the resistance of porcine arteries against bacterial collagenase in vitro degradation increased significantly after cross-linking with the epoxy compound of glutaraldehyde. The reduction of the tensile strength of the epoxy-fixed artery after bacterial collagenase degradation was more severe than in its glutaraldehyde-fixed counterpart. Generally, with increasing pH, temperature or fixative concentration, the fixation indices and denaturation temperatures of the epoxy-fixed porcine arteries increased. The results obtained in this study may be used to optimize the fixation process for developing a small-diameter biological vascular graft fixed by an epoxy compound.

[The shear bond strength of porcelain and base metal alloys for metal-ceramic crown the study of metal roughness and microstructure]

The metal-ceramic crown has become a predominant restoration in fixed prosthodontics. The base metal has the quality of lower price, high tensile strength, high elastic modulus. The base metal alloy that contain beryllium element increases fluidity and improved casting performance. Beryllium also controls surface oxidation and affects the metal ceramic bonds. Preparation of surface prior to porcelain bonding has been a subject of controversy among dental ceramists. Two ceramic base metal alloys (one alloy contains beryllium, another is not) were studied. This investigation evaluated the polishing effects of 50 microns, 100 microns aluminum oxide sandblasting, carbide bur, carborundum point and separating disk upon two base metal alloys, Rexillium III and Wiron 88. A scanning electron microscope was used to study the surface texture. The following results were obtained: 1. The most roughest surface was created with 50 microns aluminum oxide sandblasting. The carbide bur produced the least roughed surface. 2. There are specific surface texture patterns after polishing with five different grinding materials. 3. The metal surfaces treated with 50 microns and 100 microns aluminum oxide have same micro-structure pictures, but there are much more undercuts treated with 100 microns aluminum oxide. 4. The usage of carbide bur resulted in less undercuts of metal surface at two metal alloys. 5. The usage of carborundum point and disk resulted in abrasive particles that retained on the grinding metal surface at two metal alloys. 6. The surface of Wiron 88 alloy usually had wrinkle texture but not the Rexillium III alloy.

Anionic gels as vehicles for electrically-modulated drug delivery. I. Solvent and drug transport phenomena

PURPOSE

The purpose of this study was to elucidate the in vitro behavior of anionic gels as formulation matrices for electrically-modulated drug delivery. Agarose and combinations of agarose with other anionic polymers (carbomer 934P; xanthan gum) were selected and tested to evaluate their potential for drug delivery.

METHODS

Electrical current was applied by an automatic crossover power supply to minimize the current fluctuation. Hydrocortisone was selected as the model drug in order to minimize electrostatic interference with drug transport. Syneresis and drug migration were evaluated as a function of current application time and the intensity of electrical current.

RESULTS

The data show that electrical current strength and gellant content can affect both the syneresis and drug migration. A linear correlation was found between hydrocortisone loss and mass loss via the exudate. Moreover, in agarose-carbomer 934P gel systems, cumulative gel mass loss is a linear function of time at low intensities of electrical current (e.g., 0.5 mA and 1 mA). However, hydrocortisone distribution, after electrical application, is relatively asymmetric in those agarose-carbomer 934P gels (and in agarose-xanthan gum gels) in contrast to gel matrices containing only agarose.

CONCLUSIONS

In this study, the use of carbomer 934P in conjunction with agarose enables the formulator to achieve zero-order release with electrical application. Increased anisotropicity of a gel system due to the application of electrical current could alter the effectiveness of a drug delivery system.

Crosslinking characteristics of an epoxy-fixed porcine tendon: effects of pH, temperature, and fixative concentration

Injury to the anterior cruciate ligament (ACL) often results in functional instability within the knee joint and may induce a severe articular deterioration. Clinically, these patients may require an ACL reconstruction. In an attempt to develop an improved ligament prosthesis, a prototype xenograft--an epoxy-fixed porcine Achilles tendon--was developed. The study was intended to investigate the crosslinking characteristics of the epoxy-fixed porcine tendons fixed at different pHs (4.0, 7.4, 9.0, and 10.5), temperatures (4, 25, and 37 degrees C), and fixative concentrations (1, 2, or 4%). Samples of each group were taken out at various elapsed fixation periods. The crosslinking characteristics-fixation index, denaturation temperature, and moisture content-of each sample were determined. Additionally, the stiffness of the epoxy-fixed tendons under various fixation conditions was qualitatively compared. In the study it was noted that the color of porcine Achilles tendons remained natural after epoxy fixation. With increasing pH, temperature, or fixative concentration, the fixation indices and denaturation temperatures of the epoxy-fixed tendons increased. However, the fixed porcine tendons tended to be stiffer at a higher pH, temperature, or fixative concentration. The moisture contents of the epoxy-fixed tendons were relatively lower than the fresh ones, while they were approximately the same at different pHs, temperatures, and fixative concentrations. The implications of these findings for the epoxy-fixed porcine tendons in ACL reconstruction require further investigation.

[The bonding mechanisms of base metals for metal-ceramic crown microstructure analysis of bonding agent and gold bond between porcelain and base metals]

The use of base metal alloys for porcelain fused to a metal crown and bridges has increased recently because of lower price, high hardness, high tensile strength and high elastic modulus. The addition of beryllium to base metal alloys increased fluidity and improved casting fitness. Beryllium also controlled surface oxidation and bonding strength. The bonding agent and gold bonding agent also affected the bonding strength between porcelain and metal alloys. Four commercially available ceramic base alloys were studied (two alloys contained beryllium element, another two did not). The purpose of this investigation was to study the microstructure between porcelain matrix, bonding agent and alloy matrix interfaces. A scanning electron micro-probe analyzer and energy dispersive X-ray spectroscopy (EDXS) were used to study the distribution of elements (Ni, Cr, Mo, Cu, O, Si, Sn, Al) in four base alloys. The following results were obtained: 1. The thickness of the oxidized layer of Rexillium III alloy and Unitbond alloy (contained beryllium) was thinner than Unibond alloy and Wiron 88 alloy (no beryllium). 2. The thickness of the oxidized layer of alloys in air (10 minutes and 30 minutes) was thinner in Unitbond (2.45 microns and 3.80 microns) and thicker in Wiron 88 (4.39 microns and 5.96 microns). 3. The thickness of the oxidized layer occurring for a duration of ten minutes (in vaccum) showed that the Rexillium III alloy was the thinnest (1.93 microns), and Wiron 88 alloy was the thickest (2.30 microns). But in thirty minutes (vacuum), Unitbond alloy was the thinnest (3.37 microns), and Wiron 88 alloy was the thickest (5.51 microns). 4. The intensity of Cr elements was increased obviously near the interface between Unitbond alloy, Wiron 88 alloy (no beryllium) and oxidized layer, but the intensity of Ni and Mo elements was slightly increased. The intensity of Cr element was not increased markedly between Rexillium III alloy, Unitbond alloy (beryllium) and oxidized layer. 5. A white-grayish oxidized layer appeared at the metal-ceramic interfaces but the thickness of oxidized layer was not obviously different. 6. The use of bonding agent at metal-ceramic interface leads to the deposition of many Sn elements at about 40 microns range within the porcelain surface. 7. Second interaction phases at the porcelain layer appeared when gold bonding agent was used, and a 50-100 microns microleakage occurred at the metal-ceramic interface.

Recurrent epistaxis following nasotracheal intubation--a case report

Epistaxis is one of the common complications of nasotracheal intubation. Clinical patterns of all nasal bleeding are mild and may stop spontaneously in most patients. Serious nasal bleeding requiring hospitalization are rare. Nasal bleeding occurs more frequently in children than in adults. Among adults, men have a higher incidence than women. Although numerous publications have reported the cases of initial epistaxis caused by nasotracheal intubation, recurrent epistaxis was reported rarely. We experienced a case of recurrent epistaxis occurring in the 6th, 8th, 15th and 18th day after nasotracheal intubation. Herein, we describe the clinical events and discuss the causes of epistaxis.

Crosslinking characteristics of porcine tendons: effects of fixation with glutaraldehyde or epoxy

Anterior cruciate ligament (ACL) injuries, if left untreated, often produce significant disability in the athletically active population. Currently, autogenous tissue is the most commonly used substitute for ACL reconstruction because its immunogenicity is virtually nonexistent. However, the functional amount of autogenous tissue available for transplantation is limited. Additionally, this transplantation procedure may create a defect at the donor site, which can result in functional disability. To address these concerns, a prototype xenograft ligament prosthesis, epoxy-fixed porcine Achilles tendon, was developed. This study was intended to investigate the crosslinking characteristics of the epoxy-fixed porcine tendon. The fresh and glutaraldehyde-fixed porcine Achilles tendons were used as controls. Fresh porcine Achilles tendons procured from a slaughterhouse were used to fabricate the ligament prostheses. A 4% epoxy (ethylene glycol diglycidyl ether) solution or a 0.625% glutaraldehyde solution was employed to fix the porcine tendons. Samples of each group were taken out at various elapsed fixation periods. The crosslinking characteristics- denaturation temperature, moisture content, and fixation index-of each sample were then determined. In the study, it was learned that the crosslinking rate for the glutaraldehyde fixation was faster than that for the epoxy fixation. While the denaturation temperatures and the fixation indices for both studied groups were higher than for the fresh one, the denaturation temperature of the glutaraldehyde-fixed tendon was relatively higher than its epoxy-fixed counterpart. However, the fixation index and the moisture content for both studied groups were comparable. Also, it was noted that the epoxy-fixed tendon appeared more natural as compared to its glutaraldehyde-fixed counterpart. The implications of these findings for the epoxy-fixed tendon in the clinical ACL reconstruction require further investigation.

[Arytenoid subluxation following endotracheal intubation--a case report]

A previously healthy 39-yr-old man was scheduled for exploratory laparotomy due to acute abdomen. There was no sign of difficult intubation. After induction of anesthesia with thiopental and succinylcholine, the trachea was easily intubated with a 7.0 mm cuffed endotracheal tube. Surgery for a ruptured appendix with 2 drainage tubes lasted for 75 min was uneventful. At the end of surgery, the endotracheal tube was removed without difficulty. On the 1st postoperative day, the patient developed stridor. The symptom persisted even after conservative treatment and removal of NG tube. On the 12th postoperative day, a telescopic videolarygoscopy revealed immobile right vocal cord with anterior and medial displacement to the right. Arytenoid cartilage was moderately edematous. A diagnosis of right arytenoid subluxation was then made. On the 17th postoperative day, a closed reduction of right arytenoid cartilage using direct laryngoscope was performed successively under general anesthesia. Eight weeks after the reduction, his voice and laryngoscopic findings were normal. There has been only 18 reports with 27 cases of this complication found in the literature. However, it is generally believed that it is not so unusual. The post-intubation syndromes, such as sore throat, dysphonia, odynophagia, difficulty in swallowing or breathing which persists beyond 5 days warrant ENT consultation. Abnormal mobility of vocal cord, edema over arytenoid area found by indirect laryngoscopy should suggest the complication. Further confirmation is then needed. Although the result of our case is good, the reduction should ideally be done within 24-48 h after the incidence to avoid unfavorable long-term sequelae.

Serious suppurative group A beta-hemolytic streptococcal infection in previously well children: report of six cases

Recently, among adults and children, an increase in the incidence of invasive disease caused by group A beta hemolytic streptococcus (GABHS) has been noted. From December 6, 1981 to January 19, 1991, we experienced six cases of serious infection caused by GABHS in previously well children. Among them, five cases were found in recent two years. The clinical manifestations were varied. One child had sepsis, one had streptococcal toxic shock-like syndrome, two had pyogenic arthritis, and the other two newborn infants had empyema and cellulitis associated with sepsis. Early diagnosis and treatment with appropriate antibiotic are necessary for a good outcome. In addition, empyema and pyoarthritis of the hip often need surgical drainage.

[The stress distribution of prefabricated screw posts. Part III: Techniques]

Some commonly used endodontic screw posts were analysed for various techniques of post insertion by photoelastic stress distribution. These endodontic dowels were installed in assumed clinical conditions. These conditions included: (1) no backing off during post installation, (2) the channelling of the post without cleaning, (3) a smaller drill was used prepare the post channel, and (4) an axis deviated contrangle was used to prepare the post channel. According to this photoelastic analysis, the techniques of post insertion may affect the stress distribution. Suggestions for post insertion are as follows: 1. The stress can be reduced by counterrotating the dowel one-fourth turn after resistance to installation has been detected. 2. The channel should be cleaned thoroughly before post insertion. 3. Because accurate post fit is important to maximize both retention and support, the screw post should be used with the matched post/reamer system; and accurate contrangle drilling should be maintained.

The cytological diagnosis of nasopharyngeal carcinoma using a silk swab stick

A prospective study was carried out to investigate the efficacy of exfoliative cytology for the diagnosis of nasopharyngeal carcinoma. Exfoliated nasopharyngeal cells were collected from patients with a clinical suspicion of carcinoma by scraping the nasopharyngeal mucosa with a piece of silk wrapped around one end of a wooden stick. Ninety-eight patients were investigated in this manner, and the results of cytological investigation compared with the histological findings. The sensitivity of cytological investigation was 71% and the overall accuracy was 86%. The combined use of cytology and serology as a method of screening for nasopharyngeal carcinomas is discussed.

A strategy for efficient characterization of macromolecular heteroassociations via measurement of sedimentation equilibrium

A method is proposed for the selection of experimental conditions for sedimentation equilibrium experiments that will provide maximal information about the values of equilibrium association constants within a given scheme for heteroassociation of two solute components. A discriminator function is proposed that indicates the sensitivity of the experimentally observed gradient or gradients to alterations in the underlying association constants. The value of this function is plotted or tabulated as a function of the concentrations of the two components, over a broad range of solution compositions. It is suggested that experiments performed with loading compositions corresponding to large absolute values of the discriminator function will yield the most information with respect to determination of the underlying association constants. This method was tested by predicting optimal conditions for three different types of sedimentation equilibrium experiments: (i) measurement of total (natural) solute absorbance; (ii) measurement of individual component gradients via measurement of tracer absorbance; and (iii) global analysis of multiple experiments. Experimental data resulting from sedimentation equilibrium experiments carried out under the specified conditions were simulated by addition of realistic levels of random error to calculated equilibrium gradients. The simulated data were then analyzed exactly as real experimental data, i.e., without prior knowledge of the underlying association constants. It was found that the highest accuracy and precision in determination of heteroassociation constants are obtained by global analysis of multiple experiments performed using significantly different loading compositions, each of which is selected from 'sensitive' regions of the discriminator map.

Effect of isoproterenol on the uptake of [14C]glucose into glial cells

The effect of isoproterenol on the uptake of [14C]glucose into cultured glial cells was investigated in the present study. Isoproterenol markedly stimulated the uptake of [14C]glucose 30 min after incubation. This action was produced in a dose-dependent manner. A positive correlation between the increase of [14C]glucose uptake and the stimulation of adenylate cyclase induced by isoproterenol was obtained (r = 0.99). The effect of isoproterenol was reduced by the beta-adrenergic blockers but not by other blockers, indicating the selective action of isoproterenol. The results obtained suggest that isoproterenol stimulates the uptake of glucose into glial cells through the activation of beta-adrenoceptors which are linked to adenylate cyclase.

[Changes in microstructure of ceramic alloys after heat and electrochemical acid treatment]

The technique of electrochemical etching was developed by Dr. Tegart for application in both research and industry in 1959. There is considerable evidence showing that in conjunction with chemical bonding, surface roughness of etched casting restorations can apparently improve the mechanical adherence between the porcelain and the metal. It is obvious that surface roughness produced by sandblasting or electrochemical etching of the metal substrate not only provides mechanical interlocking but also increases the surface area for porcelain attachment. It was observed in this study that a properly heat-treated surface was significantly rougher than a surface without appropriate treatment after electrochemical acid etching. The roughness of base metals also treated with 0.5N nitric acid appeared greater obvious than those treated with 10% sulfuric acid. The etching pattern can be evaluated by selective removal of the alloy phases present between the dendritic arms in the base metal alloy. The technique of electrochemical acid etching is limited to alloys that solidify with a multiphasic structure- that is, a base metal alloy. And there are no known noble alloys suitable for this technique in this experiment. Electrolytic etching is most conveniently evaluated under a light microscope at about 30-80 magnifications to inspect surface relief and etching patterns. It remains to be determined by further research what is the exact cause of the increased roughness and how it improves the metal for ceramic mechanical bonding.

Shear strength of the composite bond to etched porcelain

The shear bond strength of composite resin to porcelain was investigated to optimize variables for bonding porcelain laminate veneers. Scanning electron microscopy was initially used to examine the surface configuration of porcelain prepared under various conditions. A factorial experiment was undertaken to determine the effects of three different bonding methods on both etched and non-etched porcelain. Composite resin was bonded to the porcelain groups using (a) unfilled resin, (b) silane, and (c) silane with dentin adhesive. The results indicated a significant difference in shear bond strength for the three bonding groups, depending on the porcelain surface condition. For the unetched samples, significant differences in bond strength were obtained for all three bonding conditions. However, for the etched group, there were no differences between the silane and silane-with-dentin-adhesive groups. Porcelain etching significantly increased bond strength across all three bonding methods and was the main contributor to the obtained values.