[In vitro activity of β-lactamase inhibitors avibanvctam and relebactam in combination with β-lactams against multidrug-resistant Mycobacterium tuberculosis and mutations of resistance genes]

Objective: To evaluate the activity of six β-lactams in combination with three β-lactamase inhibitors against mycobacterium tuberculosis(MTB) in vitro. Methods: A total of 105 multidrug-resistant tuberculosis (MDR-TB) strains from different regions of Henan province from January to September 2020 were included in this study. Drug activity of six β-lactams (biapenem, meropenem, imipenem, doripenem, ertapenem and tebipenem) alone or in combination with β-lactamase inhibitors (clavulanic acid, avibactam and relebactam) was examined by minimum inhibitory concentration method (MICs) against 105 clinical isolates. Mutations of blaC, ldtmt1 and ldtmt2 were analyzed by PCR and DNA sequencing. Chi-square test was used to compare the antimicrobial activities of different β-lactam drugs. Results: Out of the β-lactams used herein, tebipenem was the most effective against MDR-TB and had an MIC50 value of 8 mg/L(χ2=123.70,P=0.001). Besides, after the addition of β-lactamase inhibitors, the MICs of most β-lactam drugs were reduced more evidently in the presence of avibactam and relebactam compared to clavulanic acid.Especially, relebactam decreased both the MIC50 and MIC90 of telbipenem by 16-fold, and diluted the MIC of 23 (21.90%) and 41 (39.04%) isolatesby 32-fold and 16-fold.In addition, a total of 13.33% (14/105) of isolates harbored mutations in the blaC gene, with three different nucleotide substitutions: AGT333AGG, AAC638ACC and ATC786ATT. For the strains with Ser111Arg and Asn213Thr substitution in BlaC, the MIC values of the meropenem-clavulanate combination were reduced compared with a synonymous single nucleotide polymorphism (SNP) group. Conclusions: Both avibactam and relebactam had better synergistic effects on β-lactams than clavulanic acid. The combination of tebipenem and relebactam showed the most potent activity against MDR-TB isolates. In addition, the Ser111Arg and Asn213Thr substitution of BlaC may be associated with an increased susceptibility of MDR-TB isolates to meropenem in the presence of clavulanate.

Unintrusive multi-cancer detection by circulating cell-free DNA methylation sequencing (THUNDER): development and independent validation studies

BACKGROUND

Early detection of cancer offers the opportunity to identify candidates when curative treatments are achievable. The THUNDER study (THe UNintrusive Detection of EaRly-stage cancers, NCT04820868) aimed to evaluate the performance of ELSA-seq, a previously described cfDNA methylation-based technology, in the early detection and localization of six types of cancers in the colorectum, esophagus, liver, lung, ovary and pancreas.

PATIENTS AND METHODS

A customized panel of 161,984 CpG sites was constructed and validated by public and in-house (cancer: n=249; non-cancer: n=288) methylome data, respectively. The cfDNA samples from 1,693 participants (cancer: n=735; non-cancer: n=958) were retrospectively collected to train and validate two multi-cancer detection blood test models (MCDBT-1/2) for different clinical scenarios. The models were validated on a prospective and independent cohort of age-matched 1,010 participants (cancer: n=505; non-cancer: n=505). Simulation using the cancer incidence in China was applied to infer stage-shift and survival benefits to demonstrate the potential utility of the models in the real world.

RESULTS

MCDBT-1 yielded a sensitivity of 69.1% (64.8%‒73.3%), a specificity of 98.9% (97.6%‒99.7%) and tissue origin accuracy of 83.2% (78.7%‒87.1%) in the independent validation set. For early stage (I‒III) patients, the sensitivity of MCDBT-1 was 59.8% (54.4%‒65.0%). In the real-world simulation, MCDBT-1 achieved the sensitivity of 70.6% in detecting the six cancers, thus decreasing late-stage incidence by 38.7%‒46.4%, and increasing 5-year survival rate by 33.1%‒40.4%, respectively. In parallel, MCDBT-2 was generated at a slightly low specificity of 95.1% (92.8%-96.9%) but a higher sensitivity of 75.1% (71.9%-79.8%) than MCDBT-1 for populations at relatively high risk of cancers, and also had ideal performance.

CONCLUSION

In this large-scale clinical validation study, MCDBT-1/2 models showed a high sensitivity, specificity, and accuracy of predicted origin in detecting six types of cancers.

Development of a Novel Hybrid Suture Anchor for Osteoporosis by Integrating Titanium 3D Printing and Traditional Machining

The aim of this study is to develop a titanium three-dimensional (3D) printing novel hybrid suture anchor (HSA) with wing structure mechanism which can be opened to provide better holding power for surrounding osteoporotic bone. A screw-type anchor (5.5-mm diameter and 16-mm length) was designed with wing mechanism as well as micro dual-thread in the outer cortex bone contact area and macro single-thread in the anchor body. Both side wings can be opened by an internal screw to provide better bone holding power. The suture anchor and internal screw were manufactured using Ti6Al4V 3D printing and traditional machining, respectively. Static pullout and after dynamic 300-cyclic load (150 N) pullout tests for HSA with or without the wing open and commercial solid anchor (CSA) were performed (n = 5) in severely osteoporotic bone and osteoporotic bone to evaluate failure strengths. Comparison of histomorphometrical evaluation was performed through in vivo pig implantation of HSAs with the wing open and CSAs. The failure strengths of HSA with or without the wing open were 2.50/1.95- and 2.46/2.17-fold higher than those of CSA for static and after dynamic load pullout tests in severely osteoporotic bone, respectively. Corresponding values for static and after dynamic load pullout tests were 1.81/1.54- and 1.77/1.62-fold in osteoporotic bone, respectively. Histomorphometrical evaluation revealed that the effects of new bone ingrowth along the anchor contour for CSA and HSA were both approximately 20% with no significant difference. A novel HSA with wing mechanism was developed using 3D printing and the opened wing mechanism can be used to increase bone holding power for osteoporosis when necessary. Better failure strength of HSA than CSA under static and after dynamic load pullout tests and equivalence of bone ingrowth along the anchor contours confirmed the feasibility of the novel HSA.

Development of a micro-electrochemical machining nanosecond pulse power supply

Micro-electrochemical machining (micro-ECM) has been widely used for microscale and nanoscale processing of materials. The performance of the nanosecond pulse power supply is directly related to the precision of micro-ECM, which is one of the core technologies for micro-ECM. In this work, a nanosecond pulse power supply, with adjustable pulse frequency, duty cycle, and voltage, was designed with an STM32F103VET6 single-chip microcomputer as the control core and a metal-oxide-semiconductor field-effect transistor as the chopper switch component. The performance test has shown that the power supply can produce a continuous pulse with the highest frequency of 8 MHz, the shortest pulse width of 50 ns, the maximum peak current of 12 A, and the maximum voltage of 10 V. As compared with the power supply reported in the literature, the present power supply demonstrated the enhanced output current and improved waveform of the nanosecond pulse output, which could result in better machining accuracy and efficiency for micro-ECM.

[Synchronous robotic resection for colorectal liver metastasis]

Surgical resection remains the only curative therapy for colorectal adenocarcinoma and liver metastasis. Synchronous robotic resection for colorectal liver metastasis (CRLM) offers the advantage of avoiding double surgical stress, while providing the benefits of small incision, quicker recovery, shorter hospital stay and faster postoperative adjuvant therapy. Compared with the laparoscopic approach, robotic approach is mostly suitable for rectal cancer liver metastasis, which is associated with low conversion rate, good nerve protection, high success rate for major hepatectomy and resection of difficult segments. Appropriately selected patients, multidisciplinary cooperation and skillful robotic surgeons are the key to success. Current data have demonstrated the feasibility and safety of synchronous robotic resection for CRLM. With the coming randomized controlled trial data and evolution of robotic surgical system, the future of synchronous robotic resection for colorectal liver metastasis is promising.

[Experience of teaching and training for medical students at gastrointestinal surgery department under COVID-19 epidemic situation]

In hospitals and medical schools as densely populated sites with high risk of coronavirus disease 2019 (COVID-19), it is vital to adjust the teaching and training strategy for medical students to ensure curriculum completion with safety. This article aims to introduce the experience of teaching and training for medical students under the epidemic situation at Department of Surgery, Shanghai Medical College, Fudan University and Zhongshan Hospital. The content includes exploring diversified online teaching models for undergraduate surgery courses and clinical practice, carrying out online graduate education and dissertation plans, and strengthening comprehensive education of medical humanity combined with knowledge of COVID-19 prevention. Through implementation of the above teaching strategies, scheduled learning plans of medical students can be well completed in an orderly, safe and quality-ensured manner. Our experience provides practical solution of medical teaching and could be advisable for other medical colleges and teaching hospitals.

[Risk factors of anastomotic leakage after robotic surgery for low and mid rectal cancer]

Objective: To investigate the risk factors associated with anastomotic leakage after robotic surgery in mid-low rectal cancer. Methods: A retrospective case-control study method was conducted. Inclusion criteria: (1) 18 to 80 years old; (2) pathologically confirmed rectal cancer; (3) distance <10 cm from tumor to anal margin; (4) robotic anterior rectal resection. Patients with previous history of colorectal cancer surgery, distant metastases or other malignant tumors, undergoing emergency surgery, with severe abdominal adhesions or those receiving combined organ resection were excluded. Based on the above criteria, 636 patients undergoing robotic radical sphincter-preserving surgery for mid-low rectal cancer in Zhongshan Hospital from January 2015 to December 2018 were included in this study, including 398 males (62.6%) and 238 females (37.4%) with a mean age of (61.9±11.3) years. Sixty-eight cases (10.7%) received neoadjuvant chemoradiotherapy. Amony the 636 included patients, 123(19.3%) underwent natural orifice specimen extraction surgery (NOSES) and 15 (2.3%) underwent preventive stoma. According to the cirteria developed by the International Rectal Cancer Research Group in 2010, the anastomotic leakage was classified as grade A (no requirement of intervention), B (requirement of intervention), and C (requirement of operation). Logistic regression was used to analyze the relationship between anastomotic leakage and clinicopathological factors. Factors in univariate analysis with P<0.05 were included in the multivariate analysis. Results: Anastomotic leakage occurred in 38 cases (6.0%). The grading of anastomotic leakage was grade A in 13 cases (2.0%), grade B in 19 cases (3.0%), and grade C in 6 cases (0.9%). The 3-year disease-free survival rate of patients with anastomotic leakage and without anastomotic leakage was 83.5% and 83.6% respectively (P=0.862); the 3-year overall survival rate of the two group was 85.1% and 87.5% respectively (P=0.296). The results of univariate logistic regression analysis showed that male (P=0.011), longer operation time (P=0.042), distance ≤5 cm from tumor to anal margin (P=0.012), more intraoperative blood loss (P=0.048) were associated with anastomotic leakage (all P<0.05). NOSES was not associated with anastomotic leakage (P=0.704). Multivariate analysis confirmed that male (OR=3.03, 95%CI: 1.37 to 7.14, P=0.010), operation time ≥180 minutes (OR=2.04, 95%CI: 1.03 to 3.99, P=0.040), distance ≤5 cm from tumor to anal margin (OR=2.56, 95%CI:1.28 to 5.26, P=0.008) were independent risk factors for anastomotic leakage. Conclusion: Male, short distance from tumor to anal margin, and long operation time are independent risk factors for anastomotic leakage in patients undergoing robotic mid-low rectal cancer radical surgeries. These patients need to be cautiously treated during surgery.

[Sub-health status of middle school teachers and its correlation analysis with occupational stress]

Objective: To study the distribution of sub-health and occupational stress as well as their correlation among middle school teachers in Tianjin, then provide evidences for prevention and control of the status of sub-health. Methods: A total of 3 522 middle school teachers from six districts of Tianjin were recruited with stratified cluster sampling strategy for the investigation of Sub-Health Measurement Scale version 1.0 (SHMS V1.0) and Occupational Stress Inventory-Revised Edition (OSI-R) . Results: Detection rate of sub-health status among Tianjin middle school teachers was 58.55%. Men had significantly lower sub-health detection rate (55.19%) than women (59.71%) . Sub-health detection rate increased with age (P<0.05) , the sub-health detection rate among middle school teachers more than 50 years old was the highest (66.84%) . The mean score of OSI-R was 403.18±41.80 with the scores of 176.00±21.05, 103.17±17.53, and 124.02±20.28 for ORQ, PSQ, PRQ, respectively, which showed significantly difference compared with the occupational stress norm of China (P<0.001) . The mean scores of OSI-R, ORQ, PSQ, PRQ in different health status were significantly different (P<0.001) . The partial correlation analysis between the scores of sub-health and occupational stress of middle school teachers showed that the scores of occupational role and personal strain were negatively correlated with the scores of sub-health state (P< 0.001) , while, there was significantly positive correlation between the scores of personal resource and the scores of sub-health state (P<0.001) . Conclusion: Sub-health detection rate of middle school teachers in Tianjin is higher. Effective measures should be taken to appropriately mitigate the occupational stress level of middle school teachers, increase personal resources, and scientific and effective health guidance and education should be strengthened.

LITAF, HHEX, and DUSP1 expression in mesenchymal stem cells from patients with psoriasis

Psoriasis is a common chronic relapsing inflammatory skin disease, in which mesenchymal stem cells (MSCs) have been hypothesized to play an important role in abnormal localized inflammation and vascular proliferation observed in skin lesions. Previous studies have revealed abnormal gene expression patterns, DNA methylation status, and cytokine secretion of MSCs in psoriatic skin lesions, as well as some gene expression abnormalities related to inflammation and angiogenesis. We further verified the gene and protein expressions of inflammation-related lipopolysaccharide-induced tumor necrosis factor-alpha transcription factor (LITAF), dual-specificity protein phosphatase 1 (DUSP1), and angiogenesis-related hematopoietically expressed homeobox (HHEX) in MSCs derived from the skin lesions of psoriasis patients. The gene expression of LITAF, DUSP1, and HHEX in dermal MSCs was measured at the mRNA level using reverse transcription-polymerase chain reaction and the corresponding protein expression levels were analyzed by western blotting analysis. The gene and protein expression levels of LITAF, HHEX, and DUSP1 in dermal MSCs were significantly lower in psoriasis patients compared to controls. Amplification and western blotting results were consistent with our previously reported gene chip data. Our results suggest that dermal MSCs in psoriatic skin lesions may be involved in the development, progression, and regulation of localized inflammatory abnormalities by reducing the expression of LITAF, HHEX, and DUSP1, which are related to inflammation and angiogenesis.

Liver cancer stem cells are selectively enriched by low-dose cisplatin

Accumulating evidence has indicated the importance of cancer stem cells in carcinogenesis. The goal of the present study was to determine the effect of low-dose cisplatin on enriched liver cancer stem cells (LCSCs). Human hepatoblastoma HepG2 cells were treated with concentrations of cisplatin ranging from 1 to 5 μg/mL. Cell survival and proliferation were evaluated using a tetrazolium dye (MTT) assay. LCSCs were identified using specific markers, namely aldehyde dehydrogenase-1 (ALDH1) and CD133. The percentage of ALDH1+ or CD133+ cells was examined by flow cytometric analysis. The expression of ALDH1 and/or CD133 in HepG2 cells was determined by immunocytochemical analysis. Low-dose cisplatin treatment significantly decreased cell survival in HepG2 cells after 24 or 72 h. However, the percentage of LCSCs in the surviving cells was greatly increased. The percentage of ALDH1+ or CD133+ cells was increased in a time- and dose-dependent manner after treatment with 1-4 μg/mL cisplatin, whereas 5 μg/mL cisplatin exposure slightly reduced the number of positive cells. These findings indicate that low-dose cisplatin treatment may efficiently enrich the LCSC population in HepG2 cells.

Prospective analysis of quality of life in elderly patients treated with adjuvant chemotherapy for non-small-cell lung cancer

BACKGROUND

Given the more comorbidities with a decline in physiologic reserve, it can be challenging to make appropriate treatment decisions in the elderly.

PATIENTS AND METHODS

Here, we prospectively evaluated and compared the health-related quality of life (HRQOL) of patients aged ≥ 65 with aged <65 who were treated with a postoperative chemotherapy for completely resected stage Ib, II or IIIa non-small-cell lung cancer (NSCLC). Either four cycles of paclitaxel (Taxol)-carboplatin (PC) or vinorelbine-cisplatin (NP) was used. The HRQOL was assessed with EORTC QLQ-C30 and EORTC QLQ-LC13.

RESULTS

Between October 2008 and October 2011, a total of 139 patients (aged <65, n = 73; ≥ 65, n = 66) were enrolled, and 127 (91.4%) completed the questionnaire. Overall, the quality of life (QOL) in elderly patients did not significantly deteriorate with adjuvant chemotherapy and the time trend of QOL in elderly patients was similar to that of younger patients. Although the elderly suffered from increased treatment-related adverse events involving sore mouth, peripheral neuropathy and alopecia compared with the baseline, the same time trends were also observed in younger group. The mean dose intensities (MDIs) for PC and NP regimen were not significantly different between the two age groups.

CONCLUSIONS

Postoperative chemotherapy did not substantially reduce HRQOL in elderly NSCLC patients, and HRQOL during and after adjuvant chemotherapy did not significantly differ by age.

Biomechanical evaluation of an orthodontic mini-implant with plastic removal cap: an in-vitro experimental testing

This study evaluates the biomechanical interactions of a mini-implant using a plastic revolving cap (PRC) with translation/rotation features for optional orthodontic traction. An orthodontic mini-implant and the PRC consisting of a hexagon connection onto mini-implant with 60 degree switching unit and an extended arm to provide orthodontic wire tied at different positions. The PRC removal force was measured by pull-out testing. The PRC removal force remained larger than three times the finger pulling force (9.3N) after 5 repeated removal tests. The results for the PRC resistant testing showed that the PRC rotational resistant force (20.31±0.83N) is larger than the maximum traction force (about 4.9N) for orthodontic treatment. The mini-implant used with PRC can provide translation and rotation features to change the angles and directions of orthodontic tractions for most effective anchorage preparation under safety consideration.

Finite element sub-modeling analyses of damage to enamel at the incisor enamel/adhesive interface upon de-bonding for different orthodontic bracket bases

This study investigates the micro-mechanical behavior associated with enamel damage at an enamel/adhesive interface for different bracket bases subjected to various detachment forces using 3-D finite element (FE) sub-modeling analysis. Two FE macro-models using triangular and square bracket bases subjected to shear, tensile and torsional de-bonding forces were established using μCT images. Six enamel/adhesive interface sub-models with micro- resin tag morphology and enamel rod arrangement were constructed at the corresponding stress concentrations in macro-model results. The boundary conditions for the sub-models were determined from the macro-model results and applied in sub-modeling analysis. The enamel and resin cement stress concentrations for triangular and square bases were observed at the adhesive bottom towards the occlusal surface under shear force and at the mesial and distal side planes under tensile force. The corresponding areas under torsional force were at the three corners of the adhesive for the triangular base and at the adhesive bottom toward/off the occlusal surface for the square base. In the sub-model analysis, the concentration regions were at the resin tag base and in the region around the etched holes in the enamel. These were perfectly consistent with morphological observations in a parallel in vitro bracket detachment experiment. The critical de-bonding forces damaging the enamel for the square base were lower than those of the triangular base for all detached forces. This study establishes that FE sub-modeling can be used to simulate the stress pattern at the micro-scale enamel/adhesive interface, suggesting that a square base bracket might be better than a triangular bracket. A de-bonding shear force can detach a bracket more easily than any other force with a lower risk of enamel loss.

Estimation of the retainer height biomechanical contribution in posterior resin-bonded fixed partial dentures: a structural-thermal coupled finite element analysis

This study determines the RBFPD (resin-bonded fixed partial dentures) biomechanical aspects to retainer height using structural-thermal coupled finite element (FE) analysis under normal (37°C) and high (51°C) oral temperatures. Three RBFPD FE models with different retainer heights (100, 75, and 50% of the distance from 2 mm above the CE (cementum-enamel) junction to the occlusal surface) were created using image processing, contour stacking, and mapping mesh procedures. After FE model validation, the maximum first principal and von Mises stresses in the remaining tooth (σ(T)) and prosthesis (σ(P)), were recorded for all models under structural-thermal coupled analyses. The simulation results showed that the σ(T) and σ(p) values decreased with greater retainer height as a result of the increasing prosthesis stiffness and maximizing bonding area between the enamel and retainer at normal oral temperature (37°C). However, no significant stress differences were found according to the retainer height varying dimensions at high (51°C) temperatures. The RBFPD retainer height biomechanical response is dominated by the structural analysis result (at 37°C) and it is recommended that the prosthesis retainer have as great a height as possible to decrease the stress values.

Reductions in the effects of damping on stress concentration in premolars by post-endodontic restorations: a non-linear finite element study

The aim of this study was to measure the structural damping constants of premolars after treatment with a cast Co-Cr post-core system or permanent root filling, and to evaluate the stress damping effects of these restored premolars. Both the damping ratio and the natural frequency (NF) of the cast Co-Cr post-core restored premolars and the permanent root-filled premolars were detected by in-vitro NF testing experiments. Unprepared premolars served as the control. The damping constants beta of the samples were calculated from the measured damping ratios and natural frequencies. The measured damping constants beta of the test premolars were then used for dynamic finite element (FE) analyses. Stress contours and damping effects of stresses in each treated type of premolar were computed and compared using ANSYS. The measured damping constants beta were 0.75 x 10(-5) for the unprepared premolars, 0.69 x 10(-5) for the root-filled premolars with coronal restoration, and 0.72 x 10(-5) for the cast Co-Cr post-core restored premolars. The unprepared intact premolars demonstrated the highest stress dissipation effects with a ratio of 29.3 per cent at the middle root opposite to the loading side. However, no stress dissipation effects were found in the premolars that had been restored with the cast Co-Cr post-core system. The FE analysis showed that metallic post treatment attenuated the damping properties of the premolar. The effects of damping on stress concentration were significantly lower in restored premolars than in untreated vital premolars. These findings suggest that future research on post material should take the damping property into consideration.

Electronic structure of pyrochlore Cd(2)Re(2)O(7)

Detailed band structure calculations have been performed for Cd(2)Re(2)O(7) in high-, middle- and low-temperature (T) phases. The calculations are based on the observed lattice structures from x-ray diffraction measurements. The spin-orbit interaction is incorporated self-consistently in both the generalized gradient approximation (GGA) and the GGA plus Hubbard U (GGA+U) approaches. It is found that the on-site U has negligible effects on the Re 5d band structures; therefore both the GGA and GGA+U Re 5d band energies agree well with the observed O K-edge x-ray absorption spectroscopy (XAS) spectrum, whereas the Cd 4d band energy observed from photoemission spectroscopy can only be correctly reproduced by GGA+U calculations, indicating the relatively itinerant Re 5d and localized Cd 4d electrons. On the other hand, the spin-orbit coupling gives rise to nontrivial spin and orbital magnetic moments for the middle- T phase. Most unexpectedly, we found that the low- T phase exhibits quasi-two-dimensional Fermi surfaces. The calculated carrier numbers for the three phases are, at least qualitatively, consistent with the measured Hall coefficient.

Evaluation of the relative contributions of multi-factors in an adhesive MOD restoration using FEA and the Taguchi method

OBJECTIVES

This study determines the relative contribution of changes (design factors) in cavity dimension, restorative material, adhesive layer modulus and thickness and loading condition on the biomechanical response of a premolar adhesive Class II MOD restoration.

METHODS

A validated finite element (FE) model was used to simulate the mechanical responses. The Taguchi method was employed to identify the significance of each design factor in controlling the stress.

RESULTS

The results indicated that the loading condition was the major factor affecting the stress values (49% in tooth and 46% in cement). Cavity depth was found as the second contributor affecting the stress values (31 % in tooth and 30% in cement), followed by resin cement modulus (12% in tooth and 13% in cement). Other factors were found to have no significant effect on the tooth and cement stress values. Increased stress values were found with lateral force, deeper cavity and higher luting cement modulus.

SIGNIFICANT

The combined use of FE analysis and the Taguchi method efficiently identified the relative contributions of several restorative factors and indicated that cavity depth was the most critical factor on the cavity dimensions in attaining a proper occlusal adjustment. Reduced lateral occlusal force and lower modulus luting material application are recommended to obtain a better force-transmission mechanism.

Biomechanical interactions in tooth-implant-supported fixed partial dentures with variations in the number of splinted teeth and connector type: a finite element analysis

OBJECTIVE

The aim of this study was to investigate the biomechanical interactions in tooth-implant-supported fixed partial dentures (FPDs) under several loading conditions with different numbers of splinted teeth and connector types (rigid and non-rigid) by adopting the three-dimensional (3D) non-linear finite element (FE) approach.

MATERIAL AND METHODS

A 3D FE FPD model was constructed containing one Frialit-2 implant in the mandibular second-molar region splinted to the first and second premolars. Frictional contact elements were used to simulate realistic interface conditions within the implant system and the non-rigid connector function. The main effects for each level of the three investigated factors (loading condition, number of splinted teeth and connector type) in terms of the stress values and dissimilar mobility of the natural teeth and implant were computed for all models.

RESULTS

The results indicated that load condition was the main factor affecting the stress developed in the implant, bone and prosthesis when comparing the type of connector and the number of splinted teeth. The stress values were significantly reduced in centric or lateral contact situations once the occlusal forces on the pontic were decreased. However, the prosthesis stress for the non-rigid connections was increased more than 3.4-fold relative to the rigid connections. Moreover, the average tooth-to-implant displacement ratios (R(TID)) with a non-rigid connection were obviously larger than those for rigid connections under axial loading forces. Adding an extra tooth to support a three-unit tooth-implant FPD only exploited its function when the prosthesis withstood lateral occlusal forces.

CONCLUSIONS

The load condition is the main factor affecting stress distribution in different components (bone, prosthesis and implant) of tooth-implant-supported FPDs. Minimizing the occlusal loading force on the pontic area through selective grinding procedures could reduce the stress values obviously. A non-rigid connector may more efficiently compensate for the dissimilar mobility between the implant and natural teeth under axial loading forces but with the risk of increasing unfavorable stresses in the prosthesis.

Factorial analysis of variables influencing mechanical characteristics of a single tooth implant placed in the maxilla using finite element analysis and the statistics-based Taguchi method

The aim of this study was to determine the relative contribution of changes (design factors) in implant system, position, bone classification, and loading condition on the biomechanical response of a single-unit implant-supported restoration. Non-linear finite-element analysis was used to simulate the mechanical responses in an implant placed in the maxillary posterior region. The Taguchi method was employed to identify the significance of each design factor in controlling the strain/stress. Increased strain values were noted in the cortical bone with lateral force and an implant with a retaining-screw connection. Cancellous bone strain was affected primarily by bone type and increased with decreasing bone density. Implant stress was influenced mainly by implant type and position. The combined use of finite-element analysis and the Taguchi method facilitated effective evaluation of the mechanical characteristics of a single-unit implant-supported restoration. Implants placed along the axis of loading exhibit improved stress/strain distribution. The reduction of lateral stress through implant placement and selective occlusal adjustment is recommended. An implant with a tapered interference fit connection performed better as a force-transmission mechanism than other configurations.

Evaluation of a reinforced slot design for CEREC system to restore extensively compromised premolars

OBJECTIVES

The structural stability and adhesive strength of a large-cavity premolar with a CEREC restoration is a frequent problem in long-term use. This study sought to determine whether an additional reinforced slot could increase tooth/ceramic retention using finite element (FE) analysis and fracture testing.

METHODS

The cavity was designed in a typical MODL restoration failure shape when the lingual cusp has been lost. Two FE restored-tooth models with different cavity designs were created using image processing, contour stacking, and mesh generation. Interfacial (normal and shear) stresses were then calculated with and without the slot design for restored teeth under lateral and axial forces and different interfacial conditions (bonded and de-bonding). For validation, a fracture experiment was performed with and without reinforced slot designs for large ceramic CEREC restorations.

RESULTS

The maximum stresses at the buccal wall increased when a lateral occlusal force acted on the restored tooth with a slot design. Conversely, the interfacial stresses decreased when the restored tooth received a uniform axial occlusal force. After de-bonding on the buccal tooth/ceramic interface, the stresses increased by an average factor of three over those obtained with a bonded interface. The fracture forces were consistent with the tendencies predicted in FE analyses.

CONCLUSIONS

An additional reinforced slot for the CEREC restoration of a large cavity could increase retention when a restored tooth receives an axial occlusal load. However, the benefits of a slot seem to be doubtful for a premolar often subjected to a lateral load.

Immunohistochemical diagnosis of mouse hepatitis virus and mycoplasma pulmonis infection with murine antiserum

This study established a modified alkaline phosphatase-labelled avidin-biotin-complex (ABC-AP) method for diagnosis of mouse hepatitis virus (MHV) and Mycoplasma pulmonis infection from formalin-fixed, paraffin wax-embedded sections, murine antibody-positive serum being used as the primary reagent. With this method, MHV antigen in cAnNCrj.Cg-Foxn1(nu)/Foxn1(nu) mice and M. pulmonis antigen in Wistar rats were immunolabelled in tissue sections. MHV antigen was clearly detected in samples of liver, stomach, caecal and colonic mucosa, and spleen. M. pulmonis antigen was demonstrated on the luminal surface of bronchiolar epithelial cells. This method may prove useful in diagnosis when commercial antisera are unavailable or when immunosuppression prevents serological diagnosis.

The sequence-specific DNA binding of NF-kappa B is reversibly regulated by the automodification reaction of poly (ADP-ribose) polymerase 1

Recent studies suggest that the synthesis of protein-bound ADP-ribose polymers catalyzed by poly(ADP-ribose) polymerase-1 (PARP-1) regulates eucaryotic gene expression, including the NF-kappaB-dependent pathway. Here, we report the molecular mechanism by which PARP-1 activates the sequence-specific binding of NF-kappaB to its oligodeoxynucleotide. We co-incubated pure recombinant human PARP-1 and the p50 subunit of NF-kappaB (NF-kappaB-p50) in the presence or absence of betaNAD+ in vitro. Electrophoretic mobility shift assays showed that, when PARP-1 was present, NF-kappaB-p50 DNA binding was dependent on the presence of betaNAD+. DNA binding by NF-kappaB-p50 was not efficient in the absence of betaNAD+. In fact, the binding was not efficient in the presence of 3-aminobenzamide (3-AB) either. Thus, we conclude that NF-kappaB-p50 DNA binding is protein-poly(ADP-ribosyl)ation dependent. Co-immunoprecipitation and immunoblot analysis revealed that PARP-1 physically interacts with NF-kappaB-p50 with high specificity in the absence of betaNAD+. Because NF-kB-p50 was not an efficient covalent target for poly(ADP-ribosyl)ation, our results are consistent with the conclusion that the auto-poly(ADP-ribosyl)ation reaction catalyzed by PARP-1 facilitates the binding of NF-kappaB-p50 to its DNA by inhibiting the specific protein.protein interactions between NF-kappaB-p50 and PARP-1. We also report the activation of NF-kappaB DNA binding by the automodification reaction of PARP-1 in cultured HeLa cells following exposure to H(2)O(2). In these experiments, preincubation of HeLa cells with 3-AB, prior to oxidative damage, strongly inhibited NF-kappaB activation in vivo as well.

Natural frequency analysis of periodontal conditions in human anterior teeth

The purpose of this study was to evaluate the possibility of using natural frequency (NF) analysis to detect the attachment loss of periodontal tissue. In this study, 698 anterior teeth were examined by a conventional probing method and also by NF analysis. The teeth were triggered to vibrate with an impulse hammer, and the vibrational response was detected by an acoustic sensor. Our results demonstrate no significant difference in NF values between the upper-lower/left-right quadrants of the tested teeth, although the mean natural frequency value of central incisors with periodontal disease was found to be 1.24 +/- 0.11 kHz which is significantly lower than that of teeth in a healthy condition (1.34 +/- 0.20kHz; p < 0.01). On the other hand, the mean frequency for periodontal disease involving canines (1.28 +/- 0.09 kHz) was also significantly lower than the corresponding value for healthy analogs (1.35 +/- 0.17 kHz; p < 0.05). These results suggest that NF analysis appears to be an effective method for assessing the periodontal condition of anterior teeth. Moreover, since this method is noninvasive, nondestructive, and necessitates minimal tooth contact, it can serve as an effective method for the early quantifiable testing and prevention of periodontal disease.

Cytotoxic flavonoids with isoprenoid groups from Morus mongolica

A new pyranoflavanone, sanggenol L (1), a Diels-Alder type adduct regarded as a cycloaddition product of a dehydrogeranylflavanone and a prenylchalcone, sanggenol M (2), along with four new 2-arylbenzofurans with isoprenoid units, mulberrofurans W-Z (3-6), were isolated together with 10 known flavonoids from Chinese Morus mongolica. The structures of these novel compounds were elucidated by spectroscopic methods. All flavanones investigated here showed higher cytotoxicity against human oral tumor cell lines (HSC-2 and HSG) than against normal human gingival fibroblasts (HGF). Among them, the cytotoxicity of compound 2 and the Diels-Alder type flavanone sanggenon C (7) isolated from Morus cathayana were the most potent. On the other hand, seven 2-arylbenzofurans exhibited lower cytotoxicity and tumor specificity as compared with flavanones.

Red blood cell osmotic fragility in chronically hemodialyzed patients

Chronic renal failure induces anemia and a short erythrocyte life span. Red blood cell (RBC) osmotic fragility is the resistance of RBC hemolysis to osmotic changes that is used to evaluate RBC friability. To find the cause of shortened red cell survival in uremic patients, we evaluated the RBC osmotic fragility in 57 chronic hemodialyzed patients. Each patient had received 12 h of dialysis per week continuously prior to being enrolled in the study. Nineteen healthy volunteers served as a control group. Biochemistry, hemoglobin, electrolyte, osmolarity, beta2-microglobulin, and intact parathyroid hormone were examined before and after the dialysis session. To evaluate the osmotic fragility of RBC, blood samples were collected in heparinized test tubes. Fifty microliters of the RBC of each individual was then incubated in solutions containing a series of various concentrations of NaCl ranging from 0 to 0.6%. The concentration of NaCl at which 50% of RBCs were lysed was considered the median osmotic fragility (MOF). The results showed that the MOF was significantly greater in hemodialyzed patients before dialysis than in the control group (0.41 +/- 0.03 vs. 0.39 +/- 0.02%). The osmotic resistance to hemolysis was also recorded after dialysis (MOF 0.38 +/- 0.03%). Correlation analysis showed that the MOF was significantly correlated with urea nitrogen, serum osmolarity, and intact parathyroid hormone level. In addition, the osmotic fragility was higher in patients who had a predialysis intact parathyroid hormone level > 100 pg/dl. In conclusion, hemodialysis can improve the osmotic fragility. The mechanism underlying this improvement may be the removal of low molecular weight uremic toxins, resulting in normalization of serum osmolarity. Our results indicate that parathyroid hormone is probably a major factor influencing RBC osmotic fragility in chronic renal failure.

Diagnosis and management of allergic fungal sinusitis with orbital involvement

PURPOSE

Allergic fungal sinusitis (AFS) is a noninvasive disease characterized by recurrent sinusitis. This condition is commonly treated with surgical debridement and several months of systemic corticosteroids. The treatment of AFS is examined in this study.

METHODS

A retrospective case series of three patients with AFS.

RESULTS

All three patients were treated with surgical debridement and less than one month of systemic corticosteroids. The patients then were treated with intranasal corticosteroids and monitored closely. Antifungal therapy was not used. All three patients remained disease-free during follow-up ranging from 12 months to 36 months.

CONCLUSIONS

Surgical debridement and systemic corticosteroids for less than four weeks followed by intranasal corticosteroids may provide long-term control of AFS. Additional study is recommended to examine further the optimal treatment for AFS.

The effects of two different cisplatin-based chemotherapy regimens on advanced non-small cell lung cancer

BACKGROUND

Many different cisplatin-based regimens have been used on advanced non-small cell lung cancer (NSCLC) in previous studies but there have been few such references in Taiwan. In this study, we evaluated the efficacy and toxicity of two different regimens including 5-Fluorouracil, Leucovorin, Etoposide and cisPlatin (FLEP) and cisPlatin, Etoposide and Mitomycin (PEM) in the treatment of patients with advanced NSCLC.

METHODS

We retrospectively analyzed the records of 44 patients with NSCLC who met the selection criteria from February 1995 through April 1998. All of them were confirmed, using histologic tests, that they were in advanced stages, i.e. stage IIIB or IV. Twenty-two patients received FLEP and 22 patients received PEM.

RESULTS

Three patients with FLEP therapy and 3 patients with PEM therapy had partial response. No patient had complete response. The response rate was 13.6% in both groups, respectively. The median survival was 160 +/- 30 (median + SD) days for patients with FLEP therapy and 263 +/- 104 days for patients with PEM therapy. The factors that were associated with longer survival in all patients included response (Stable Disease vs Disease Progression p = 0.004, Partial Response vs Disease Progression p = 0.047) and regimen of chemotherapy (PEM vs FLEP p = 0.008). The major clinically significant toxicity was myelosupression.

CONCLUSION

The responses to regimens, FLEP and PEM, were low in our study groups that might be due to the low dose of cisplatin and etoposide in our regimens. The patients with response to chemotherapy and PEM therapy had longer median survival than those who underwent FLEP therapy.

Periocular atypical mycobacterial infections

OBJECTIVE

To examine the clinical characteristics and management of periocular infections caused by atypical mycobacteria.

DESIGN

Retrospective, noncomparative case series.

PARTICIPANTS

Six patients were identified with periocular atypical mycobacterial infections: four with Mycobacterium chelonae and two with Mycobacterium fortuitum.

INTERVENTION

The treatment of these infections included removal of the foreign bodies with debridement of the lesions. Specimens were sent for histopathologic examination, routine cultures, and fresh tissue for culture after homogenization.

MAIN OUTCOME MEASURES

A retrospective review of culture-proven atypical mycobacterial infections involving the periocular tissues was performed. Charts were reviewed for age, gender, infectious organism, medical history, surgical history, presenting symptoms, clinical features, and treatment.

RESULTS

Four associations with infection were identified in these patients: immunosuppression, nasolacrimal duct obstruction, the presence of a foreign body, and a history of recent surgery. All six of the patients had at least one of these associations and five of the patients had at least two. Clinical characteristics that may distinguish atypical mycobacterial infections from acute bacterial infections include subacute presentation, firm nodular lesions, mild erythema, mild tenderness, and minimal purulent discharge. All patients had resolution of their infections after debridement and several weeks of systemic antibiotic therapy guided by susceptibility testing.

CONCLUSIONS

Periocular atypical mycobacterial infections are uncommon. The clinical history and examination can raise the suspicion of this infection by revealing the clinical characteristics of these infections. Treatment includes removal of foreign bodies, debridement, and long-term systemic antibiotic therapy.

Skeletal muscle contractions stimulate cGMP formation and attenuate vascular smooth muscle myosin phosphorylation via nitric oxide

Nitric oxide generated by neuronal nitric oxide synthase in contracting skeletal muscle fibers may regulate vascular relaxation via a cGMP-mediated pathway. Neuronal nitric oxide synthase content is greatly reduced in skeletal muscles from mdx mice. cGMP formation increased in contracting extensor digitorum longus muscles in vitro from C57 control, but not mdx mice. The increase in cGMP content was abolished with NG-nitro-L-arginine. Sodium nitroprusside treatment increased cGMP levels in muscles from both C57 and mdx mice. Skeletal muscle contractions also inhibited phenylephrine-induced phosphorylation of smooth muscle myosin regulatory light chain. Arteriolar dilation was attenuated in contracting muscles from mdx but not C57 mice. NO generated in contracting skeletal muscle may contribute to vasodilation in response to exercise.

Delay of estradiol-induced surge secretion of LH in gilts by intracerebroventricular injection of morphine

In Experiment 1, ovariectomized (OVX) gilts, 143 d old and 58.5 +/- 1.8 kg BW, received 10 micrograms estradiol benzoate (EB)/kg BW i.m. and either 500 micrograms of the endogenous opioid peptide (EOP) agonist, morphine (MOR), in saline (SAL; n = 5), or SAL (n = 4) intracerebro-ventricularly at 40 and 48 hr after EB. With the exception of one MOR-treated gilt, which was deleted from Experiment 1, LH secretion was suppressed for at least 50 hr in all gilts. Timing of the LH surge was similar among gilts. However, total LH secreted was greater (P < 0.05) after SAL than MOR. The experiment was repeated at 179 d of age and 78.6 +/- 1.2 kg BW, except that treatments were reversed among gilts. Emergence of the LH surge was delayed (P < 0.005) by 10.8 hr and time to maximum LH concentration (P < 0.05) by 6.8 hr after MOR than after SAL. Magnitude and total LH secreted were not different among gilts. In Experiment 2, gilts which had displayed estrous cycles of 18-22 d were OVX and treated as in Experiment 1, except MOR (n = 3) or SAL (n = 4) were injected 10 hr later than in Experiment 1, i.e., at 50 and 58 hr after EB. Secretion of LH was suppressed for at least 60 hr in both groups. Time to emergence of the LH surge was delayed by 27 hr (P < 0.05) after MOR compared to after SAL. However, other parameters of the surge were not different among gilts. Thus, EOP modulate LH surge secretion negatively in the pig.

A color Doppler analysis of nifedipine-induced posterior ocular blood flow changes in open-angle glaucoma

PURPOSE

This pilot study used color Doppler imaging to investigate the effects of nifedipine on the posterior ocular blood flow of patients with glaucoma progression at normal intraocular pressures.

PATIENTS AND METHODS

Eighteen patients, 11 men and seven women with a median age of 61.7 years, were imaged before and 6 weeks after the initiation of 30 mg of sustained-release nifedipine (Procardia XL; produced by either Pfizer or Pratt) daily.

RESULTS

There was no statistically significant change in the blood velocity of the ophthalmic artery, central retinal artery, and main nasal and temporal short posterior ciliary arteries after treatment with nifedipine.

CONCLUSION

The routine use of nifedipine in patients with normal tension glaucoma progression is not supported by this study.

Plasma spraying of zirconia-reinforced hydroxyapatite composite coatings on titanium: part II: dissolution behaviour in simulated body fluid and bonding degradation

The change of phase, morphology and bond strength of plasma sprayed hydroxyapatite (HA) coating and ZrO2/HA composite coatings immersed in simulated body fluid (SBF) for various periods of time was studied. X-ray diffractometry (XRD) and scanning electron microscopy (SEM) were used to identify the phase and observe the morphology of the coating surface before and after immersion. In addition, inductively coupled plasma emission spectroscopy (ICP) was used to measure the ion release rate of coatings in SBF for various periods of time. Observation of the morphology by SEM shows that the composite coating with the addition of ZrO2 in HA significantly reduced the dissolution rate of impurity phases in simulated body fluid. The argument was supported by measurement of Ca2+ ion concentration in SBF. During plasma spraying, less OH- ions were lost in a ZrO2-containing composite coating. This factor, together with the reduced effective surface of the ZrO2-containing HA coating, were attributed to the reduced dissolution rate of the composite coatings. All the plasma sprayed coatings degraded after immersion in SBF owing to dissolution of constituents in the coating, however, the addition of ZrO2 in HA improved the bonding strength of HA coating after immersion in SBF.

Plasma spraying of zirconia-reinforced hydroxyapatite composite coatings on titanium: part I: phase, microstructure and bonding strength

Plasma-sprayed hydroxyapatite (HA) coatings applied to metal substrates can induce a direct chemical bond with bone and hence achieve biological fixation of the implant. However, the poor bonding strength between HA and substrate has been of concern to orthopaedists. In this study, two submicrometre ZrO2 powders stabilized with both 3 and 8 mol% Y2O3 (TZ3Y and TZ8Y, respectively) were incorporated in a plasma-sprayed HA coating on Ti-6Al-4V substrate to investigate the change in phase, microstructure and bonding strength. The results show that ZrO2 composite coatings contain more unmelted particles and greater porosity. During plasma spraying, ZrO2 reacts with the CaO in HA to form CaZrO3 and accelerates HA decomposition to alpha-TCP and Ca4P2O9. Nevertheless, bonding strength increases with increase of ZrO2 content in the range 0 to 10 wt% studied. The higher Y2O3-containing TZ8Y apparently exerts a greater strengthening effect than the lower Y2O3-containing TZ3Y.

Intensive chemotherapy plus recombinant human granulocyte-colony stimulating factor support for distant metastatic nasopharyngeal carcinoma. A preliminary report

Nasopharyngeal carcinoma (NPC) has been shown to be highly responsive to chemotherapy. The major limiting toxicity was myelotoxicity. Recently, the role of granulocyte colony-stimulating factor (G-CSF) in reducing chemotherapy-induced neutropenic sepsis has been well established. In this study, we tested whether recombinant human G-CSF (rhG-CSF) could effectively support the bone marrow function in both previously untreated and pretreated metastatic NPC patients receiving intensive chemotherapy. Twelve patients with distant metastatic disease, 5 newly diagnosed (group A) and 7 pretreated patients (group B), were enrolled to receive BEC (bleomycin, epirubicin and cisplatin), followed by rhG-CSF support (50 microg/m2 s.c. daily for 10 days) every 4 weeks for two cycles. Four patients in group A completed the treatment as scheduled while only 2 patients in group B did. After the first treatment cycle, 6 patients (50%) had grade III-IV myelosuppression. Five of the patients were from group B. The mean values of the white cell count nadir were 2,680 (range 1,200-3,700) in group A and 1,343 (range 400-2,900) in group B (p = 0.0386). Neutropenia-associated fever occurred in 7 patients, 6 of whom had received previous treatment. There were 2 deaths due to toxicity, and both patients had liver metastases within 6 months following radiation. After 24 months of follow-up, only 1 patient is still alive. Our preliminary results suggest that in previously treated metastatic NPC patients, bone marrow suppression is still the major limiting toxic side effect of aggressive chemotherapy, especially for those patients with liver recurrences within 6 months after irradiation and despite rhG-CSF support.

Spontaneous orbital hemorrhage in pregnant women treated with subcutaneous heparin

PURPOSE

To describe two pregnant women who developed spontaneous orbital hemorrhage following treatment with subcutaneous heparin.

METHOD

Case histories and subsequent management of spontaneous orbital hemorrhage.

RESULTS

Both women developed severe unilateral visual loss.

CONCLUSION

In spontaneous orbital hemorrhage, anticoagulation therapy such as heparin may contribute to severe hemorrhage and visual loss.

Neuronal nitric oxide synthase and dystrophin-deficient muscular dystrophy

Neuronal nitric oxide synthase (nNOS) in fast-twitch skeletal muscle fibers is primarily particulate in contrast to its greater solubility in brain. Immunohistochemistry shows nNOS localized to the sarcolemma, with enrichment at force transmitting sites, the myotendinous junctions, and costameres. Because this distribution is similar to dystrophin, we determined if nNOS expression was affected by the loss of dystrophin. Significant nNOS immunoreactivity and enzyme activity was absent in skeletal muscle tissues from patients with Duchenne muscular dystrophy. Similarly, in dystrophin-deficient skeletal muscles from mdx mice both soluble and particulate nNOS was greatly reduced compared with C57 control mice. nNOS mRNA was also reduced in mdx muscle in contrast to mRNA levels for a dystrophin binding protein, alpha 1-syntrophin. nNOS levels increased dramatically from 2 to 52 weeks of age in C57 skeletal muscle, which may indicate a physiological role for NO in aging-related processes. Biochemical purification readily dissociates nNOS from the dystrophin-glycoprotein complex. Thus, nNOS is not an integral component of the dystrophin-glycoprotein complex and is not simply another dystrophin-associated protein since the expression of both nNOS mRNA and protein is affected by dystrophin expression.

Biogenic amines in the hypothalamus of rats after diethyldithiocarbamate or AIMAX treatment, an alternative for norepinephrine depletion

The objective of this study was to determine whether AIMAX (a dithiocarbamoylhydrazine derivative) is suitable for determining the effects of norepinephrine (NE) depletion on reproduction in domestic animals. Therefore, the effect of AIMAX (n = 6) on concentrations of biogenic amines in the medial basal hypothalamus (MBH) and anterior hypothalamic area (AHA) of ovariectomized (OVX) rats primed with ovarian steroids was compared to that of diethyldithiocarbamate (DDC; n = 5), a potent dopamine-beta-hydroxylase (DBH) inhibitor, which is chemically similar to AIMAX. Rats that received only ovarian steroids and saline injections served as controls (n = 6). Treatment with DDC resulted in sedation and reduced body temperature. In contrast, rats behaved normally after AIMAX treatment. AI-MAX reduced (P < .05) NE but increased (P < .05) dopamine (DA) concentrations in MBH and AHA compared with controls. Similar changes in NE and DA concentrations were observed in DDC-treated rats. However, elevated epinephrine (EPI) levels were measured in MBH and AHA of only DDC-treated rats. Serum LH concentrations were suppressed (P < .005) in both AIMAX- and DDC-treated rats compared with control animals. Because AIMAX, like DDC, suppressed hypothalamic NE content and LH secretion, AIMAX should be useful in studying effects of NE depletion on gonadotropin secretion in domestic animals.

Opioid modulation of gonadotropin releasing hormone release from the hypothalamic preoptic area in the pig

Two experiments (Exp) were conducted to examine in vitro the release of gonadotropin releasing hormone (GnRH) from the hypothalamus after treatment with naloxone (NAL) or morphine (MOR). In Exp 1, hypothalamic-preoptic area (HYP-POA) collected from 3 market weight gilts at sacrifice and sagittally halved were perifused for 90 min prior to a 10 min pulse of morphine (MOR; 4.5 x 10(-6) M) followed by NAL (3.1 x 10(-5) M) during the last 5 min of MOR (MOR + NAL; n = 3). The other half of the explants (n = 3) were exposed to NAL for 5 min. Fragments were exposed to KCl (60 mM) at 175 min to assess residual GnRH releasability. In Exp 2, nine gilts were ovariectomized and received either oil vehicle im (V; n = 3); 10 micrograms estradiol-17 beta/kg BW in 42 hr before sacrifice (E; n = 3); .85 mg progesterone/kg BW in twice daily for 6 d prior to sacrifice (P4; n = 3). Blood was collected to assess pituitary sensitivity to GnRH (.2 microgram/kg BW) on the day prior to sacrifice. On the day of sacrifice HYP-POA explants were collected and treated as described in Exp 1 except tissue received only NAL. In Exp 1, NAL increased (P < .05) GnRH release. This response to NAL was attenuated (P < .05) by coadministration of MOR. Cumulative GnRH release after NAL was greater (P < .05) than after MOR + NAL. All tissues responded similarly to KCl with an increase (P < .05) in GnRH release.(ABSTRACT TRUNCATED AT 250 WORDS)

Purification and characterization of smooth muscle cell caveolae

Plasmalemmal caveolae are a membrane specialization that mediates transcytosis across endothelial cells and the uptake of small molecules and ions by both epithelial and connective tissue cells. Recent findings suggest that caveolae may, in addition, be involved in signal transduction. To better understand the molecular composition of this membrane specialization, we have developed a biochemical method for purifying caveolae from chicken smooth muscle cells. Biochemical and morphological markers indicate that we can obtain approximately 1.5 mg of protein in the caveolae fraction from approximately 100 g of chicken gizzard. Gel electrophoresis shows that there are more than 30 proteins enriched in caveolae relative to the plasma membrane. Among these proteins are: caveolin, a structural molecule of the caveolae coat; multiple, glycosylphosphatidylinositol-anchored membrane proteins; both G alpha and G beta subunits of heterotrimeric GTP-binding protein; and the Ras-related GTP-binding protein, Rap1A/B. The method we have developed will facilitate future studies on the structure and function of caveolae.

N-methyl-d,l-aspartate modulation of pituitary hormone secretion in the pig: role of opioid peptides

Sixteen ovariectomized (OVX) mature gilts, averaging 139.6 +/- 3.1 kg body weight (BW) were assigned randomly to receive either progesterone (P, 0.85 mg/kg BW, n = 8), or corn oil vehicle (OIL, n = 8) injections im twice daily for 10 d. On the day of experiment, all gilts received either the EAA agonist, N-methyl-d,l-aspartate (NMA; 10 mg/kg BW, iv) alone or NMA plus the EOP antagonist, naloxone (NAL, 1 mg/kg BW, iv), resulting in the following groups of 4 gilts each: OIL-NMA, OIL-NMA-NAL, P-NMA and P-NMA-NAL. Blood samples were collected via jugular cannula every 15 min for 6 hr. All pigs received NMA 5 min following pretreatment with either 0.9% saline or NAL 2 hr after blood collection began and a GnRH challenge 3 hr after NMA. Administration of NMA suppressed (P < 0.03) LH secretion in OIL-NMA gilts and treatment with NAL failed to reverse the suppressive effect of NMA on LH secretion in OIL-NMA-NAL gilts. Similar to OIL-NMA gilts, NMA decreased (P < 0.03) mean serum LH concentrations in P-NMA gilts. However, in P-NMA-NAL gilts, serum LH concentrations were not changed following treatment. All gilts responded to GnRH with increased (P < 0.01) LH secretion. Additionally, administration of NMA increased (P < 0.01) growth hormone (GH) and prolactin (PRL) secretion in both OIL-NMA and P-NMA gilts, but this increase in GH and PRL secretion was attenuated (P < 0.01) by pretreatment with NAL in OIL-NMA-NAL and P-NMA-NAL gilts.(ABSTRACT TRUNCATED AT 250 WORDS)

Involvement of the central noradrenergic system in opioid modulation of luteinizing hormone and prolactin secretion in the pig

The role of norepinephrine (NE) in the progesterone (P)-dependent endogenous opioid peptide (EOP) suppression of LH and prolactin (PRL) secretion in the pig was studied. Fifteen ovariectomized gilts treated with P (0.85 mg/kg b.w. i.m.) twice daily for 10 days were assigned, 5 gilts each, to the following treatment groups: 1) control, 2) AIMAX (N-methyl-N1[1-methyl-2-propenyl]1,2 hydrazinedicarbothioamide), and 3) anti-GnRH serum. On day 4 of P treatment, AIMAX (125 mg per 1.8 kg feed/day), previously shown to be an NE synthesis inhibitor, was fed daily for 7 days to group 2. On the last day of P treatment, group 3 gilts received an i.v. injection of anti-GnRH serum at 0800 h while Group 1 animals received an i.v. injection of serum collected from hypophysectomized gilts. Jugular blood samples were collected every 15 min for 9 h starting at 1000 h. All gilts received two injections of naloxone (NAL; 1 mg/kg b.w., i.v.) at 1400 h and 1600 h and an injection of a GnRH analogue (D-[Ala6-desGly-NH10]-ethylamide; 5 micrograms/pig, i.v.) at 1800 h. Pretreatment serum LH concentrations were lower (p < 0.05) in AIMAX-treated gilts (0.19 +/- 0.09 ng/ml) than in controls (0.53 +/- 0.09 ng/ml), but were similar to those in GnRH antiserum-treated gilts (0.32 +/- 0.09 ng/ml). NAL increased (p < 0.001) serum LH concentrations in control animals and averaged 1.6 +/- 0.2 ng/ml the first h. AIMAX and anti-GnRH serum blocked the NAL-induced LH secretion. Serum PRL concentrations averaged 6.0 +/- 0.1 ng/ml for all groups.(ABSTRACT TRUNCATED AT 250 WORDS)

Toxoplasma gondii peritonitis

Toxoplasma gondii most often causes encephalitis in HIV-infected patients; infections of other organs are much less often clinically apparent. In particular, peritonitis caused by T. gondii in an Human Immunodeficiency Virus (HIV)-infected patient has been reported only once previously. Herein we report a second case.

Growth hormone secretion, serum, and cerebral spinal fluid insulin and insulin-like growth factor-I concentrations in pigs with streptozotocin-induced diabetes mellitus

Diabetes mellitus was induced using streptozotocin in five gilts between 8 and 12 weeks of age. Gilts were maintained with exogenous insulin (INS) except during experimental periods. Four litter-mate gilts served as controls. At 9 months of age, all gilts were ovariectomized, and 30 days after ovariectomy, Experiment (Exp) 1 was conducted. Jugular vein catheters were inserted and blood samples were collected every 10 min for 8 hr. Experiment 2 was conducted when gilts were 11 months of age. Venous blood and cerebrospinal fluid (CSF) samples were collected in the absence (Phase I) or presence (Phase II) of INS therapy. In Experiment 1, plasma glucose concentrations were greater (P < 0.05) in diabetic (465 +/- 17 mg/100 ml) than in control (82 mg +/- 17 mg/100 ml) gilts, whereas serum INS was lower (P < 0.0001) in diabetic gilts (0.3 +/- 0.02 vs 0.9 +/- 0.05 ng/ml) and insulin-like growth factor-I was similar in diabetic and control gilts (32 +/- 3 vs 43 +/- 4 ng/ml, respectively). Mean serum GH concentration was 2-fold greater (P < 0.02) in diabetics (2.8 +/- 0.4 ng/ml) than in control gilts (1.2 +/- 0.2 ng/ml). Diabetic gilts exhibited a greater (P < 0.05) number of GH pulses than control gilts (3.2 +/- 0.4 vs 1.5 +/- 0.3/8 hr, respectively). In addition, GH pulse magnitude was markedly elevated (P < 0.02) in diabetic (5.8 +/- 0.4 ng/ml) compared with control gilts (3.3 +/- 0.6 ng/ml). Mean basal serum GH concentrations were greater (P < 0.07) in diabetic (2.2 +/- 0.5 ng/ml) compared with control gilts (1.0 +/- .1 ng/ml). In Experiment 2, CSF concentrations of insulin-like growth factor-I, INS, GH, and protein were similar for diabetic and control gilts in both phases. Serum GH levels were similar for diabetics and controls in Phase I, but were greater (P < 0.05) in diabetics than in controls in Phase II. CSF glucose levels were greater in diabetic than in control gilts in both the presence (P < 0.003) and absence (P < 0.0002) of INS therapy, whereas plasma glucose was greater (P < 0.003) in diabetic than in control gilts in the absence of INS, but returned to control concentrations in the presence of INS. However, serum GH levels were unchanged after INS therapy in the diabetic gilts. In conclusion, altered GH secretion in the diabetic gilt may, in part, be due to elevated CSF glucose concentrations, which may alter GH-releasing hormone and/or somatostatin secretion from the hypothalamus.