Hyperbaric Oxygen Therapy Attenuates the Whole Brain Radiotherapy-Induced Progressive Cognitive Dysfunction via Promoting Hippocampal Neurogenesis in Rats

PURPOSE/OBJECTIVE(S)

Radiation therapy is a widely used brain tumor treatment; however, it can cause significant effects on the central nervous system, including neurogenesis impairment, microglia activation, and oxidative stress, leading to brain injury. Hyperbaric oxygen therapy (HBOT) has been shown to benefit various neurological conditions, but its effect on radiation-induced brain injury damage remains limited. This study aims to investigate the impact of HBOT on radiation-induced neurogenesis impairment, microglia activation, and lipid peroxidation levels, and also aim to assess the therapeutic potential of HBOT on preventing irradiation-induced brain injury.

MATERIALS/METHODS

This study used a rat model that delivered different doses (2, 4, 10 Gy) of whole-brain radiation therapy (WBRT). The rats were divided into two groups: one received HBOT, and the other acted as the control (normal baric air, NBA) group. HBOT was performed on day 8 of post-radiation once per day for five consecutive days a week for four weeks. The rats were subjected to different irradiation dosages as described, followed by administration of 5-chloro-2'-deoxyuridine (CldU) immediately at day 0 or day 0 to day 7 and 5-iodo-2'-deoxyuridine (IdU) at day 2 or day 14 to day 28 following WBRT to detect serially replicating cells. Then the rats underwent behavioral tests to assess their cognitive and motor function every week. Brain tissues were collected and analyzed to evaluate neurogenesis, microglia activation, lipid peroxidation, and antioxidant levels using immunofluorescence stain and ELISA on days 7 and 28 of post-WBRT.

RESULTS

The radial maze was used to measure spatial learning and memory in rats. Compared with the 0 Gy-WBRT group, the 2 Gy-, 4 Gy-, and 10 Gy-WBRT groups of rats displayed a significant increase in latency. Seven days of post-WBRT, the newly proliferation cells (IdU positive) and serial replicating cells (CldU+IdU double positive) in the hippocampal dentate gyrus were significantly increased but were coupled with apoptosis. The alterations in the cellular composition of the dentate gyrus area were observed on days 7 and 28 post-WBRT, including increased newborn neuroblast and neuron, but half underwent apoptosis, which is associated with microglia phagocytosis and results in cognitive impairment. The lipid peroxidation was significantly increased on day 28 of post-WBRT. HBOT improves cognitive function by attenuating the WBRT-induced lipid oxidation, newly-formed cell apoptosis, and microglia phagocytosis.

CONCLUSION

Our present study suggests that HBOT may have a potential role in mitigating the effects of irradiation-induced brain injury by maintaining neurogenesis and reducing lipid peroxidation.

International Consensus Statement on Obstructive Sleep Apnea

BACKGROUND

Evaluation and interpretation of the literature on obstructive sleep apnea (OSA) allows for consolidation and determination of the key factors important for clinical management of the adult OSA patient. Toward this goal, an international collaborative of multidisciplinary experts in sleep apnea evaluation and treatment have produced the International Consensus statement on Obstructive Sleep Apnea (ICS:OSA).

METHODS

Using previously defined methodology, focal topics in OSA were assigned as literature review (LR), evidence-based review (EBR), or evidence-based review with recommendations (EBR-R) formats. Each topic incorporated the available and relevant evidence which was summarized and graded on study quality. Each topic and section underwent iterative review and the ICS:OSA was created and reviewed by all authors for consensus.

RESULTS

The ICS:OSA addresses OSA syndrome definitions, pathophysiology, epidemiology, risk factors for disease, screening methods, diagnostic testing types, multiple treatment modalities, and effects of OSA treatment on multiple OSA-associated comorbidities. Specific focus on outcomes with positive airway pressure (PAP) and surgical treatments were evaluated.

CONCLUSION

This review of the literature consolidates the available knowledge and identifies the limitations of the current evidence on OSA. This effort aims to create a resource for OSA evidence-based practice and identify future research needs. Knowledge gaps and research opportunities include improving the metrics of OSA disease, determining the optimal OSA screening paradigms, developing strategies for PAP adherence and longitudinal care, enhancing selection of PAP alternatives and surgery, understanding health risk outcomes, and translating evidence into individualized approaches to therapy.

Comparative Efficacy of Obstructive Sleep Apnea Patients Undergoing Multilevel Surgery Followed by Upper Airway Stimulation Versus Isolated Upper Airway Stimulation

PURPOSE

Upper Airway Stimulation (UAS) of the hypoglossal nerve is a rapidly growing management option for patients with obstructive sleep apnea (OSA). Our study compares the treatment efficacy of UAS between those who were initially ineligible for UAS but subsequently met eligibility after multilevel surgery versus those who underwent isolated UAS for the treatment of moderate to severe OSA.

METHODS

The investigators implemented a retrospective single-center cohort study of patients aged 18+ years who presented for surgical evaluation of OSA from 2016-2019 and underwent UAS implantation. The predictor variable was eligibility status for UAS. Initially ineligible subjects were defined as having an apnea-hypopnea (AHI) > 65 events/hr, body mass index (BMI) > 32 kg/m², or complete concentric collapse (CCC) on drug-induced sleep endoscopy. Eligible subjects were defined as having an AHI between 15 and 65, with no CCC on drug-induced sleep endoscopy. The primary outcome was change in AHI which was measured preoperatively and 6 months post UAS implantation. Secondary outcomes were change in Epworth sleepiness scale and Fatigue severity scale. Covariates were age, sex, and BMI. Data analysis involved descriptive statistics and multivariable statistical models; P < .05 was considered significant.

RESULTS

Thirty six patients underwent UAS implantation from 2016-2019. Eighteen patients who were initially ineligible for UAS underwent multilevel surgery, including uvulopalatopharyngoplasty, distraction osteogenesis maxillary expansion, or maxillomandibular advancement. Mean age was 62.4 ± 9 years and BMI of 29.1 ± 4 kg/m² with 5 female patients. The cohort of 17 patients who met criteria for UAS from the start had a mean age of 62.9 ± 14 years and mean BMI of 26.7 ± 4 kg/m² with 2 female patients. Mean AHI reduction for the multilevel group was 37.6 ± 21.2 events per hour (P < .001). Mean AHI reduction for the UAS-only group was 31.5 ± 13 events per hour (P < .001). When adjusted for age, BMI, and sex, the multilevel group had a more significant reduction (18 AHI events) compared to the isolated group (P < .001).

CONCLUSIONS

For patients who are ineligible for UAS due to severity of OSA or CCC of the velum, multilevel surgery including maxillomandibular advancement followed by UAS confers effective post-treatment results, which was superior to the UAS-only group.

Passing The Scalpel: A Student Initiative in Identifying and Addressing Unmet Needs in Dental Education

PURPOSE

Becoming an oral-maxillofacial surgeon is often challenging for young trainees. The purpose of this manuscript is to explore how a student-led group, which emphasizes networking, mentorship, and academic opportunities, may impact one's journey to becoming an oral-maxillofacial surgeon.

PATIENTS AND METHODS

This was a cross-sectional descriptive study where a 5-question Likert-type survey was administered to students who matriculated into residency and participated in a student-led group called Passing The Scalpel (PTS). This survey evaluated the value of PTS in providing exposure, career decision-making, networking/mentorship, and camaraderie. The results were analyzed, and statistical outcomes were evaluated.

RESULTS

There was an 80.5% response rate (n = 29). Question 1 regarding first exposure to oral-maxillofacial surgery had a mean score of 2.55 (standard deviation [SD] = 1.35; χ² = 15.39; P < .05). Question 2 regarding choosing oral-maxillofacial surgery as a career had a mean score of 3.66 (SD = 1.11; χ² = 10.84; P < .05). Question 3 regarding offering mentorship and networking had a mean score of 4.14 (SD = 0.92; χ² = 27.81; P < .05). Question 4 regarding increasing applicant camaraderie had a mean score of 4.21 (SD = 0.77; χ² = 36.71; P < .05). Question 5 regarding the importance of PTS within a dental curriculum had a score of 4.48 (SD = 0.68; χ² = 41.89; P < .05).

CONCLUSION

PTS is an effective student-led initiative that emphasizes early exposure, networking, and mentorship opportunities and encourages students in choosing oral-maxillofacial surgery as a specialty. PTS demonstrates that student-led initiatives can fulfill unmet needs in the dental curriculum.

Does the Lack of Gender-Specific Apnea-Hypopnea Index Cutoff for Obstructive Sleep Apnea Impact Surgical Selection?

PURPOSE

The apnea-hypopnea index (AHI) is the parameter on which the severity of obstructive sleep apnea (OSA) is based and is also the determinant for both clinicians and third-party payers for surgical procedures. The purpose of this retrospective cross-sectional chart review is to examine differences in symptoms and AHI between men and women with OSA and whether this may impact timing and selection of surgical care.

METHODS

Retrospective cross-sectional study of patients aged 18 years and older who presented at a single center for surgical evaluation of OSA from January 2017 to 2020. AHI, oxygen desaturation index, respiratory disturbance index, and lowest oxygen saturation were obtained from polysomnography. The predictor variable was gender, and the outcome variable was AHI. Unadjusted and multivariate adjusted linear regression models were used to compare differences in AHI between gender, controlling for age, body mass index (BMI), Epworth sleepiness scale, and fatigue severity scale. Poisson regression analysis with robust error was used to assess the relative risks of antidepressant and anxiolytic medication use between genders.

RESULTS

A total of 408 consecutive new patients seen for surgical evaluation to treat OSA (248 men and 160 women) were included. Median patient age was 40 years for men and 41 years for women. Median AHI for men was 22.1 events per hour and 13.7 for women (P < .001). When adjusted for age and BMI, men have 33.2% higher AHI than women, with age contributing to 2% and BMI contributing to 6% of the difference. When controlling for age, BMI, Epworth sleepiness scale, and fatigue severity scale, women have a 2.2 increased relative risk of taking anxiolytic or antidepressant medications.

CONCLUSIONS

Women with OSA seeking surgery in a dedicated sleep practice have 33% lower AHI than men when controlling for age, BMI, and symptoms. Based on our findings, non-gender-specific AHI may handicap the surgeon from offering the full range of available procedures to women with OSA.

Palatopharyngoplasty Resolves Concentric Collapse in Patients Ineligible for Upper Airway Stimulation

OBJECTIVE

To determine if a modified tissue-preserving palatopharyngoplasty could convert retropalatal concentric collapse to anteroposterior or lateral patterns of collapse on drug-induced sleep endoscopy (DISE) in patients who are not candidates for upper airway stimulation due to complete circumferential collapse at the velum.

METHODS

A prospective, nonconsecutive, single-blinded cohort study was performed by two sleep surgeons at a tertiary care center from 2015 to 2018. Inclusion criteria included adults > 18 years of age with a diagnosis of obstructive sleep apnea with an Apnea-Hypopnea Index (AHI) > 15, a body mass index (BMI) < 32, and < 25% central apneas on polysomnography. Twelve patients with complete circumferential collapse underwent a modified palatopharyngoplasty. Postoperatively, a repeat sleep study was performed. A repeat DISE was recommended for those with incomplete surgical response (clinically and/or AHI).

RESULTS

Twelve patients with complete circumferential collapse were eligible for the study. Mean BMI was 30.5. Mean preoperative AHI was 54.0 events per hour. Following a modified palatopharyngoplasty, the mean AHI was reduced to 33.1 events per hour, and 100% (12 of 12) of the patients converted from a pattern of complete circumferential collapse to either no collapse at the level of the velum (3) or an anteroposterior pattern of collapse (9).

CONCLUSION

We demonstrate that a modified palatopharyngoplasty can successfully convert collapse patterns in patients with complete circumferential collapse. Further studies are required to determine the outcome of these patients following upper airway stimulation implantation.

LEVEL OF EVIDENCE

1B Laryngoscope, 2020.

Importance of Content and Format of Oral Health Instruction to Low-income Mexican Immigrant Parents: A Qualitative Study

PURPOSE

This study's purpose was to explore how content and format of children's oral health instruction in the dental clinic is perceived by parents and might affect parents' knowledge and behaviors.

METHODS

Thirty low-income Mexican immigrant parents of children age five years and under were recruited from dental clinics in 2015 to 2016. In-person qualitative interviews in Spanish about their children's and their own experiences of dental care and home oral hygiene practices were conducted, digitally recorded, translated, and transcribed. Data analysis involved iteratively reading text data and developing and refining codes to find common themes.

RESULTS

Twenty-five of 30 parents recalled receiving oral hygiene instruction, and 18 recalled receiving nutrition instruction and were included in analyses. The format and effectiveness of instruction varied. More engaging educational approaches were recalled and described in more detail than less engaging educational approaches. As a result of oral hygiene and nutritional instruction, most parents reported changing their oral hygiene home behaviors for their children; half aimed to reduce purchasing sugary foods and drinks.

CONCLUSIONS

Most parents recalled receiving oral hygiene and nutrition instruction as part of their child's dental visit and reported incorporating the instruction and recommendations they received into their children's home routine.

Polyphosphazene Toughened PMR-type Thermosets

Two new polyphosphazenes, poly(4-maleimidophenoxy/phenoxy)phosphazene and poly(4-phthalimidophenoxy/phenoxy)phosphazene, were prepared and used to toughen a PMR polyimide designated LaRCTMRP46. These toughened polyimides were evaluated as thin films with a 0–40 wt% range of polyphosphazene to polyimide. The structure–property relationships of these inorganic/organic polymeric matrices were studied and evaluated in terms of fracture toughness, thermo-oxidative stability, and thermal, mechanical, and tensile properties. The hybrid systems revealed an increase in fracture toughness up to 20 wt% polyphosphazene load without any substantial loss in tensile properties. With 5 wt% poly(4-phthalimidophenoxy/phenoxy)phosphazene loading, the fracture toughness of the semi-interpenetrating network was increased by 124%. When 10 wt% poly(4- maleimidophenoxy/phenoxy)phosphazene loading was used, the fracture toughness of the grafted copolymer was improved by 217%. In addition, substantial enhancement in thermo-oxidative stability was also observed.

Orientation contrast of secondary electron images from electropolished metals

Orientation contrast obtained by an in-lens secondary electron detector in a scanning electron microscope from electropolished/etched metals is reported. The imaging conditions for obtaining such orientation contrast are defined. The mechanism responsible for the formation of the orientation contrast is explained, and an application example of this new imaging method is given.

A forced running wheel system with a microcontroller that provides high-intensity exercise training in an animal ischemic stroke model

We developed a forced non-electric-shock running wheel (FNESRW) system that provides rats with high-intensity exercise training using automatic exercise training patterns that are controlled by a microcontroller. The proposed system successfully makes a breakthrough in the traditional motorized running wheel to allow rats to perform high-intensity training and to enable comparisons with the treadmill at the same exercise intensity without any electric shock. A polyvinyl chloride runway with a rough rubber surface was coated on the periphery of the wheel so as to permit automatic acceleration training, and which allowed the rats to run consistently at high speeds (30 m/min for 1 h). An animal ischemic stroke model was used to validate the proposed system. FNESRW, treadmill, control, and sham groups were studied. The FNESRW and treadmill groups underwent 3 weeks of endurance running training. After 3 weeks, the experiments of middle cerebral artery occlusion, the modified neurological severity score (mNSS), an inclined plane test, and triphenyltetrazolium chloride were performed to evaluate the effectiveness of the proposed platform. The proposed platform showed that enhancement of motor function, mNSS, and infarct volumes was significantly stronger in the FNESRW group than the control group (P<0.05) and similar to the treadmill group. The experimental data demonstrated that the proposed platform can be applied to test the benefit of exercise-preconditioning-induced neuroprotection using the animal stroke model. Additional advantages of the FNESRW system include stand-alone capability, independence of subjective human adjustment, and ease of use.

Neuroprotective effect of agmatine in rats with transient cerebral ischemia using MR imaging and histopathologic evaluation

PURPOSE

This study aimed to further investigate the effects of agmatine on brain edema in the rats with middle cerebral artery occlusion (MCAO) injury using magnetic resonance imaging (MRI) monitoring and biochemical and histopathologic evaluation.

MATERIALS AND METHODS

Following surgical induction of MCAO for 90min, agmatine was injected 5min after beginning of reperfusion and again once daily for the next 3 post-operative days. The events during ischemia and reperfusion were investigated by T2-weighted images (T2WI), serial diffusion-weighted images (DWI), calculated apparent diffusion coefficient (ADC) maps and contrast-enhanced T1-weighted images (CE-T1WI) during 3h-72h in a 1.5T Siemens MAGNETON Avanto Scanner. Lesion volumes were analyzed in a blinded and randomized manner. Triphenyltetrazolium chloride (TTC), Nissl, and Evans Blue stainings were performed at the corresponding sections.

RESULTS

Increased lesion volumes derived from T2WI, DWI, ADC, CE-T1WI, and TTC all were noted at 3h and peaked at 24h-48h after MCAO injury. TTC-derived infarct volumes were not significantly different from the T2WI, DWI-, and CE-T1WI-derived lesion volumes at the last imaging time (72h) point except for significantly smaller ADC lesions in the MCAO model (P<0.05). Volumetric calculation based on TTC-derived infarct also correlated significantly stronger to volumetric calculation based on last imaging time point derived on T2WI, DWI or CE-T1WI than ADC (P<0.05). At the last imaging time point, a significant increase in Evans Blue extravasation and a significant decrease in Nissl-positive cells numbers were noted in the vehicle-treated MCAO injured animals. The lesion volumes derived from T2WI, DWI, CE-T1WI, and Evans blue extravasation as well as the reduced numbers of Nissl-positive cells were all significantly attenuated in the agmatine-treated rats compared with the control ischemia rats (P<0.05).

CONCLUSION

Our results suggest that agmatine has neuroprotective effects against brain edema on a reperfusion model after transient cerebral ischemia.

Exploration of edge-dependent optical selection rules for graphene nanoribbons

Optical selection rules for one-dimensional graphene nanoribbons are explored based on the tight-binding model. A theoretical explanation, through analyzing the velocity matrix elements and the features of the wavefunctions, can account for the selection rules, which depend on the edge structure of the nanoribbon, i.e., armchair or zigzag edges. The selection rule of armchair nanoribbons is ΔJ = Jc - Jv = 0, and the optical transitions occur from the conduction to the valence subbands of the same index. Such a selection rule originates in the relationships between two sublattices and between the conduction and valence subbands. On the other hand, zigzag nanoribbons exhibit the selection rule |ΔJ| = odd, which results from the alternatively changing symmetry property as the subband index increases. Furthermore, an efficient theoretical prediction on transition energies is obtained by the application of selection rules, and the energies of the band-edge states become experimentally attainable via optical measurements.

Magnetic and quantum confinement effects on electronic and optical properties of graphene ribbons

Through the tight-binding calculation, we demonstrate that magnetic and quantum confinements have a great influence on the low-energy band structures of one-dimensional (1D) armchair graphene ribbons. The magnetic field first changes 1D parabolic bands into the Hall-edge states which originate in the Landau wavefunctions deformed by one or two ribbon edges. The quantum confinement dominates the characteristics of the Hall-edge states only when the Landau wavefunctions touch two ribbon edges. Then, some of the Hall-edge states evolve as the Landau states when the field strength grows. The partial flat bands (Landau levels), related to the Landau states, appear. The magnetic field dramatically modifies the energy dispersions and it changes the size of the bandgap, shifts the band-edge states, destroys the degeneracy of the energy bands, induces the semiconductor-metal transition and generates the partial flat bands. The above-mentioned magneto-electronic properties are completely reflected in the low-frequency absorption spectra--the shift of peak position, the change of peak symmetry, the alteration of peak height, the generation of new peaks and the change of absorption edges. As a result, there are magnetic-field-dependent absorption frequencies. The findings show that the magnetic field could be used to modulate the electronic properties and the absorption spectra.

Electronic and optical properties of finite carbon nanotubes in an electric field

The effects, caused by the geometric structure and an electric field (E), on the electronic and optical properties of quasi-zero-dimensional finite carbon nanotubes are explored by employing the tight-binding model coupled with curvature effects. Electronic properties (state energies, symmetry of electronic states, energy spacing and state degeneracy) are significantly affected by the magnitude and the direction of the electric field and the geometric structure (radius, length and chirality). The electric field, by lowering the symmetry of finite carbon nanotubes, modifies the electronic properties. Thus, the optical excitation spectra, excited by electric polarization parallel to the nanotube axis, exhibit rich delta-function-like peaks, which reveal the characteristics of the electronic properties. Therefore it follows that geometric structure and E influence the low-energy absorption spectra, i.e. the change of frequency of the first peak, the alternation of the peak height and the production of the new peaks. There are more absorption peaks when E is oriented closer to the cross-section plane. Moreover, the very complicated optical absorption spectra are characteristic for the individual chiral carbon nanotube due to its specific geometric structure. Above all, the predicted absorption spectra and the associated electronic properties could be verified by optical measurements.

Low-energy electronic properties of the AB-stacked few-layer graphites

In the presence of a perpendicular electric field, the low-energy electronic properties of the AB-stacked N-layer graphites with layer number N = 2, 3, and 4, respectively, are examined through the tight-binding model. The interlayer interactions, the number of layers, and the field strength are closely related to them. The interlayer interactions can significantly change the energy dispersions and produce new band-edge states. Bi-layer and four-layer graphites are two-dimensional semimetals due to a tiny overlap between the valence and conduction bands, while tri-layer graphite is a narrow-gap semiconductor. The electric field affects the low-energy electronic properties: the production of oscillating bands, the cause of subband (anti)crossing, the change in subband spacing, and the increase in band-edge states. Most importantly, the aforementioned effects are revealed completely in the density of states, e.g. the generation of special structures, the shift in peak position, the change in peak height, and the alteration of the band gap.

Heat shock protein 72 overexpression protects against hyperthermia, circulatory shock, and cerebral ischemia during heatstroke

This study extends our earlier studies in rats by applying our heatstroke model to a new species. Additionally, transgenic mice are used to examine the role of heat shock protein (HSP) 72 in experimental heatstroke. Transgenic mice that were heterozygous for a porcine HSP70i gene ([+]HSP72), transgene-negative littermate controls ([−]HSP72), and normal Institute of Cancer Research strain mice (ICR) under pentobarbital sodium anesthesia were subjected to heat stress (40°C) to induce heatstroke. In [−]HSP72 or ICR, the values for mean arterial pressure, the striatal blood flow, and the striatal Po2after the onset of heatstroke were significantly lower than those in preheat controls. The core and brain temperatures, the extracellular concentrations of ischemic and injury markers in the striatum, and the striatal neuronal damage scores were significantly greater than those in the preheat controls. In [−]HSP72 or ICR, the body temperatures, cell ischemia content, and injury marker in the striatum were significantly higher, and the mean arterial pressure, striatal blood flow, and striatal Po2concentration were significantly lower during heatstroke than in [+]HSP72. Accordingly, the latency and the survival times for [+]HSP72 significantly exceeded those of [−]HSP72 or ICR. These results demonstrate that the overexpression of HSP72 in multiple organs improves survival during heatstroke by reducing hyperthermia, circulatory shock, and cerebral ischemia and damage in mice.

Evaluation of the effects of methylprednisolone pulse therapy in patients with systemic lupus erythematosus with brain involvement by Tc-99m HMPAO brain SPECT

Methylprednisolone pulse therapy (MPT) was introduced to avoid life-threatening complications in patients with systemic lupus erythematosus (SLE) with brain manifestations; however, the efficacy of MPT in SLE patients with brain involvement is still uncertain and needs to be objectively evaluated. We enrolled 15 female SLE patients with neuropsychiatric manifestations in this study. All patients had normal brain MRI and abnormal brain HMPAO-SPECT findings. Follow-up HMPAO-SPECT studies were conducted 2 weeks after MPT. Serum levels of anticardiolipin antibodies (ACA) and anti-ribosomal P antibodies (anti-P) were measured before and after MPT. Before MPT, 7 patients were positive for ACA and 7 patients were positive for anti-P. After MPT, none of the 15 patients demonstrated positive serologic findings or neuropsychiatric manifestations. Based on the follow up brain HMPAO-SPECT images following MPT, 13 patients showed disappearance of the perfusion defects and 2 patients showed partial recovery of rCBF. Brain HMPAO-SPECT imaging is a logical and objective tool for measuring the effects of MPT in SLE patients with brain involvement by determining of changes in rCBF.

Magnolol protects against cerebral ischaemic injury of rat heatstroke

1. Free radicals mediate cerebral ischaemic injury associated with heatstroke. Magnolol, an active component of Magnolia officinalis, is 1000-fold more potent than alpha-tocopherol in inhibiting lipid peroxidation in rat mitochondria. The aim of the present study was to ascertain whether magnolol attenuated cerebral ischaemic injury and free radical formation associated with heatstroke. 2. Urethane-anaesthetized rats were exposed to heat stress (ambient temperature 42 degrees C) to induce heatstroke. Controlled rats were exposed to 24 degrees C. Mean arterial pressure, cerebral perfusion pressure and cerebral blood flow after the onset of heatstroke were all significantly lower than in control rats. However, colonic temperature, intracranial pressure, heart rate, cerebral free radicals, lipid peroxidation and the neuronal damage score were greater after the onset of heatstroke. 3. Magnolol (20 or 40 mg/kg, i.v.) significantly attenuated the heatstroke-induced hyperthermia, arterial hypotension, intracranial hypertension, cerebral ischaemia and neuronal damage and increased free radical formation and lipid peroxidation in the brain. The extracellular concentrations of ischaemic (e.g. glutamate and lactate/pyruvate ratio) and damage (e.g. glycerol) markers in the corpus striatum were increased after the onset of heatstroke. Magnolol significantly attenuated the increase in striatal ischaemia and damage markers associated with heatstroke. 4. Thus, it appears that magnolol has impressive effects against heatstroke reactions.

Abnormal regional cerebral blood flow on 99mTc ECD brain SPECT in patients with primary Sjögren's syndrome and normal findings on brain magnetic resonance imaging

OBJECTIVE

Technetium-99m ethyl cysteinate dimer (99mTc ECD) single photon emission computed tomography (SPECT) of the brain was used to detect abnormal regional cerebral blood flow (rCBF) in patients with primary Sjögren's syndrome (pSS) and normal findings on brain magnetic resonance imaging (MRI).

METHODS

(99m)Tc ECD brain SPECT was performed to detect brain lesions showing hypoperfusion in 32 female patients with pSS and definite neuropsychiatric symptoms or signs. Seventeen female patients with pSS without neuropsychiatric symptoms and signs were included as a control group for comparison. All of the 49 patients with pSS had normal findings on brain MRI.

RESULTS

99mTc ECD brain SPECT showed brain regions with hypoperfusion in 18 (56.3%) of the 32 patients, and parietal lobes were the most common areas with such lesions. By contrast, 99mTc ECD brain SPECT showed brain regions with hypoperfusion in only three (17.6%) of the 17 patients with pSS without neuropsychiatric symptoms or signs.

CONCLUSION

This study suggests that 99mTc ECD SPECT is a sensitive tool for detecting regions of hypoperfusion in the brains of patients with pSS and neuropsychiatric symptoms or signs and normal findings on brain MRI. However, a review of the literature showed that the (99m)Tc ECD SPECT findings in patients with pSS were non-specific.

Positive association of ankylosing spondylitis with homozygous HLA-B2704, but protection with B2705 in Taiwan Chinese

The study was undertaken to determine the effects of HLA-B27 subtypes on susceptibility to ankylosing spondylitis (AS) in Taiwan Chinese, a polymerase chain reaction-restrictive fragment length polymorphism (PCR-RFLP) method was developed for subtyping of HLA-B27. In this series, there are 62 patients with AS who were tested HLA-B27 positive serologically and 738 normal persons over the age of 65. Among the 738 normal controls, 42 (5.7%) were HLA-B27 positive. There were six (14.3%) homozygous for B2704, 18 (42.9%) heterozygous for B2704, 2 (4.8%) double heterozygous for B2704 and B2705, one (2.3%) double heterozygous for B2704 and B2706, 2 (4.8%) homozygous for B2705, 11 (26.1%) heterozygous for B2705, and 2 (4.8%) heterozygous for B2706. In our patients with AS, 37 (59.7%) were homozygous for B2704 and 25 (40.3%) were heterozygous for B2704. The HLA-B27 carrier rate in Taiwan healthy old persons is estimated at 5.7%. Susceptibility to AS is determined by homozygosity for B2704. However, B2705 may be an indicator of protection against AS in Taiwan Chinese.

Molecular analysis of SMN, NAIP and P44 genes of SMA patients and their families

Mutations of the telomeric survival motor neuron gene (SMN1) are related to spinal muscular atrophy (SMA). However, no phenotype-genotype correlation has been observed since the SMN1 gene is lacking in the majority of patients affected with either the severe form (type I) or the milder forms (types II and III). Here, we analyze the SMN, NAIP and P44 genes in 132 Chinese SMA patients and their families. At least three types of normal allele, and four types of mutant allele were found in this study. The combination of one normal allele with one mutant allele resulted in carriers of different types, and the combination of different mutant alleles accounted for the different genotypes among different types of SMA. Deletions of mutant alleles can be further subgrouped into four types, which includes involving SMN1, SMN1 and NAIP(T) (telomeric portion of NAIP gene), SMN1 and NAIP(T) and P44(T) (telomeric portion of P44 gene), and SMN1 and SMN2 (centromeric portion of SMN gene). Some of the severe (type I) SMA cases correlated with the extent of deletions in the SMN, NAIP and P44 genes or the dosage of SMN gene when both SMN1 and SMN2 are deleted. We also found two novel point mutations, an A insertion at codon 8 (AGT-->AAGT) and an A substitution at codon 228 (TTA-->TAA).

Optimal treatment for distal ureteral calculi: extracorporeal shockwave lithotripsy versus ureteroscopy

BACKGROUND

The optimal treatment for distal ureteral calculi remains controversial. We present data from our institution to compare the efficacy of extracorporeal shockwave lithotripsy (SWL) and ureteroscopy with different lithotripsy modalities (URSL).

METHODS

From January 1994 to September 1997, 954 distal ureteral calculi were treated at our institution using in situ SWL (Siemens Lithostar) in 524 patients and ureteroscopy (Wolf 8.0F instrument and Swiss Lithoclast) in 430 patients. Stone sizes and patient ages were similar in these two groups.

RESULTS

In the SWL group, the 3-month stone-free rate was 87%, and the effectiveness quotient (EQ) was 68.7%. In the URSL group, there was a 96% stone-free rate with an EQ of 92.1%. The SWL treatment was more expensive than URSL.

CONCLUSION

At our institution, ureteroscopy is more efficacious than SWL for the treatment of distal ureteral calculi. In selected patients who had stones >10 mm with evidence of impaction and severe colic pain, we strongly suggest that URSL is the best choice.

Positional importance of Pro53 adjacent to the Arg49-Gly50-Asp51 sequence of rhodostomin in binding to integrin alphaIIbbeta3

Rhodostomin (RHO), a disintegrin isolated from snake venom, has been demonstrated to inhibit platelet aggregation through interaction with integrin alphaIIbbeta3, but there is a lack of direct evidence for RHO-integrin alphaIIbbeta3 binding. In addition, no study on the length of Arg(49)-Gly(50)-Asp(51) (RGD) loop of RHO influencing on its binding to integrin alphaIIbbeta3 has been reported. In the present study we have developed a highly sensitive dot-blot and glutathione S-transferase-RHO pull-down assays; the latter was coupled with a biotin-avidin-horseradish peroxidase enhanced-chemiluminescence detection system. These were able to demonstrate the direct binding of RHO to integrin alphaIIbbeta3. The pull-down assay further showed that four alanine-insertion mutants upstream of the RGD motif and three insertions downstream of the RGD were able to decrease integrin alphaIIbbeta3 binding activity to only a limited extent. By contrast, two insertions immediately next to RGD and one insertion in front of the Cys(57) caused almost complete loss of binding activity to alphaIIbbeta3. The results of the platelet-aggregation-inhibition assay and platelet-adhesion assay for the insertion mutants were consistent with results of the pull-down assay. It is thus concluded that, although an insertion of a single alanine residue in many positions of the RGD loop has only minor effects on RHO binding to integrin alphaIIbbeta3, the specific position of Pro(53) residue adjacent to the RGD sequence is important for RHO binding to platelet integrin alphaIIbbeta3.

A nitric oxide-dopamine link pathway in organum vasculosum laminae terminalis of rat brain exerts control over blood pressure

1. Experiments were carried out to explore the possible role played by the nitric oxide (NO) and dopamine (DA) system in the organum vasculosum laminae terminalis (OVLT) of rat brain in arterial pressure regulation. 2. Intracerebroventricular (ICV) administration of NO donors such as hydroxylamine or sodium nitroprusside (SNP) caused an up to 59 mmHg decrease in blood pressure (BP) and a decrease in DA release (measured by nafion coated carbon fibre electrodes in combination with voltammetry) in the OVLT. In contrast, ICV administration of N(G)-nitro-L-arginine methyl ester (L-NAME; a constitutive NO synthase inhibitor) or 7-nitroindazol (a neuronal NO synthase inhibitor) caused an up to 98 mmHg increase in BP and an increase in DA release in the OVLT. 3. Intra-OVLT injection of amphetamine (0.1 - 0.3 mg), SKF 38393 (a DA D(1) receptor agonist; 0.01 - 0.03 mg), or apomorphine (a DA D(2,3) receptor agonist; 0.01 - 0.03 mg) caused an increase in BP. On the other hand, intra-OVLT injection of SCH23390 (a DA D(1) receptor antagonist; 0.005 - 0.020 mg) or haloperidol (0.005 - 0.020 mg) caused a decrease in BP. 4. The pressor effects induced by intra-OVLT administration of L-NAME were attenuated by pretreatment with intra-OVLT injection of haloperidol, SCF23390, or 6-hydroxydopamine. In the contrast, the hydroxylamine-, 8-Br-cGMP- or SNP-induced depressor effects were attenuated by pretreatment with intra-OVLT injection of amphetamine, SKF 38393 or apomorphine. 5. The data suggest that activation of a NO-DA link pathway within the OVLT of rat brain exerts control over blood pressure.

Ligand-inducible interaction of the DRIP/TRAP coactivator complex with retinoid receptors in retinoic acid-sensitive and -resistant acute promyelocytic leukemia cells

Retinoic acid (RA) signaling is mediated by its nuclear receptors RXR and RAR, which bind to their cognate response elements as a heterodimer, RXR/RAR, and act in concert with coregulatory factors to regulate gene transcription on ligand binding. To identify specific cofactors that interact with the RXR/RAR heterodimer in acute promyelocytic leukemia (APL) cells, a double cistronic construct was used that allowed coexpression of the RXR LBD (ligand binding domain) with the RAR LBD as an affinity matrix to pull down interacting proteins from nuclear extracts prepared from a human APL cell line, NB4. A group of proteins was detected whose interaction with RXR/RAR is ligand inducible. The molecular weight pattern of these proteins is similar to that of a complex of proteins previously identified as DRIP or TRAP, which are ligand-dependent transcription activators of VDR and TR, respectively. The RXR/RAR-interacting proteins from NB4 were confirmed to be identical to the DRIP subunits by comparative electrophoresis, Western blot analysis, and in vitro protein interaction assay. In addition to RXR/RAR, the DRIP component can interact directly with the APL-specific PML-RARalpha fusion protein. The same DRIP complex is present in RA-resistant APL cells and in a variety of cancer cell lines, supporting its global role in transcriptional regulation.

The DRIP complex and SRC-1/p160 coactivators share similar nuclear receptor binding determinants but constitute functionally distinct complexes

Transcriptional activation requires both access to DNA assembled as chromatin and functional contact with components of the basal transcription machinery. Using the hormone-bound vitamin D(3) receptor (VDR) ligand binding domain (LBD) as an affinity matrix, we previously identified a novel multisubunit coactivator complex, DRIP (VDR-interacting proteins), required for transcriptional activation by nuclear receptors and several other transcription factors. In this report, we characterize the nuclear receptor binding features of DRIP205, a key subunit of the DRIP complex, that interacts directly with VDR and thyroid hormone receptor in response to ligand and anchors the other DRIP subunits to the nuclear receptor LBD. In common with other nuclear receptor coactivators, DRIP205 interaction occurs through one of two LXXLL motifs and requires the receptor's AF-2 subdomain. Although the second motif of DRIP205 is required only for VDR binding in vitro, both motifs are used in the context of an retinoid X receptor-VDR heterodimer on DNA and in transactivation in vivo. We demonstrate that both endogenous p160 coactivators and DRIP complexes bind to the VDR LBD from nuclear extracts through similar sequence requirements, but they do so as distinct complexes. Moreover, in contrast to the p160 family of coactivators, the DRIP complex is devoid of any histone acetyltransferase activity. The results demonstrate that different coactivator complexes with distinct functions bind to the same transactivation region of nuclear receptors, suggesting that they are both required for transcription activation by nuclear receptors.

Mutation analysis of the putative tumor suppressor gene PTEN/MMAC1 in hepatocellular carcinoma

Loss of heterozygosity of chromosome 10q has been reported in hepatoma. Areas with a high rate of loss of genetic material could harbor putative tumor suppressor genes. PTEN/MMAC1, a candidate tumor suppressor gene located at chromosome 10q23.3, has recently been identified and found to be homozygously deleted or mutated in several different types of human tumors. To determine whether the PTEN/MMAC1 gene is a target of 10q loss of heterozygosity in hepatoma, we examined 42 primary hepatomas for mutations in PTEN/MMAC1 by using nested reverse transcriptase polymerase chain reaction (RT-PCR) of the RNA and single-stranded conformation polymorphism (SSCP) analysis of all genomic exons. Although 2 of 42 hepatoma tissues had aberrant transcripts, 5 matched noncancerous liver tissues also had aberrant transcripts. Southern blot analysis of the entire genomic DNA revealed no genomic change. Therefore, like the TSG101 or FHIT gene, aberrant transcripts of PTEN/MMAC1 using the nested RT-PCR method were a common phenomenon for both cancerous and noncancerous liver tissues, which may not be related to oncogenesis. None of the 42 cases had small deletions, point mutations, or insertions. Our results suggest that the PTEN/MMAC1 gene may not play a role in the pathogenesis of hepatoma.

Development of a microplate assay for serum chromogranin A (CgA): establishment of normal reference values and detection of elevated CgA in malignant diseases

Chromogranin A (CgA), a marker for neuroendocrine cells, is associated with poor prognosis when detected by immunohistochemical technique in prostate tumors. We have developed an ELISA on microplates for serum CgA and established the normal reference range. We also attempted to find out whether elevated serum CgA levels could be found in patients with various malignant diseases. Because of non-Gaussian distribution, both medians and 97.5 percentiles of serum CgA levels for men and women of four different age groups were determined. For women, the median and 97.5 percentiles are 20.7 and 63.9 ng/mL for ages 20 to 50, and 32 and 93.8 for 50 to 80 years of age, respectively; for men, they are 27.9 and 78.4 ng/mL for ages 18 to 40 and 41.6 and 92 for 40 to 80 years old, respectively. Elevated serum concentrations of CgA were detectable in patients with prostate cancer not undergoing hormonal treatment, and in patients with various malignant diseases including nonendocrine carcinomas. Most elevated serum CgA levels were associated with sera containing highly elevated serum tumor markers. Drugs targeting neuroendocrine cells should be administered for cancer patients with elevated serum CgA levels.

Analysis of the mRNA transcripts of the survival motor neuron (SMN) gene in the tissue of an SMA fetus and the peripheral blood mononuclear cells of normals, carriers and SMA patients

Spinal muscular atrophy (SMA) is a disorder characterized by degeneration of the anterior horn cells of the spinal cord. The gene most highly associated with SMA is the survival motor neuron (SMN) gene. In this study, we present an analysis of messenger RNA (mRNA) expression of the SMN gene in peripheral blood mononuclear cells in normal subjects, SMA carriers and patients from 20 SMA families. We found at least 6-8 different transcripts of SMN gene formed by alternative splicing involving exons 3, 5 and 7. We compared transcripts from the different types of SMA and found no definite differences in transcript patterns and amounts. Normal subjects with the telomeric SMN (SMN(T)) gene only had variable splicing resulting in several transcripts, the most dominant being a transcript containing all coding regions. However, SMA patients with the centromeric SMN (SMN(C)) gene only had a higher degree of splice variation and tended to show little or no exon 7. These results demonstrate that SMN(T) and SMN(C) genes participate in alternative splicing phenomena. The different splicing patterns support the view that the SMN(T) gene is responsible for SMA disease. We also analyzed the transcripts from several tissues of an SMA fetus who had a homozygous SMN(T) gene deletion. Different splicing patterns were also found in these tissues, and were similar to the splicing pattern of leukocytes. We compared the major transcripts from exons 4 to 8 of both the SMN(T) and SMN(C) genes and found that the relative proportion varied among normal subjects, SMA carriers and patients. This approach could be used as a novel diagnostic method. We suggest that analyzing the mRNA expression of the SMN gene in peripheral blood mononuclear cells offers an apparently reliable technique for separating SMA patients, carriers, and normal individuals.

Mutation analysis of the putative tumor suppressor gene PTEN/MMAC1 in cervical cancer

OBJECTIVE

PTEN/MMAC1, a candidate tumor suppressor gene located at chromosome 10q23.3, was recently identified and found to be homozygously deleted or mutated in several different types of human tumors. The aim of this study is to determine whether PTEN/MMAC1 is a target for 10q loss of heterozygosity in cervical cancer.

METHOD

We examined 50 primary cervical carcinoma specimens using a PCR-based assay followed by SSCP and direct sequencing. The genomic DNA was also confirmed by Southern blot analysis.

RESULTS

All specimens except one, which has a 7-base deletion, showed a negative result. Among them, 30 randomly selected cases and their paired noncancerous tissue were further screened using nested RT-PCR. Six of 30 cervical cancerous tissues had aberrant transcripts. However, 4 of the matched noncancerous tissues also had aberrant transcripts. Southern blot analysis of the entire genomic DNA did not reveal any evidence of gene alteration.

CONCLUSIONS

Sequence abnormalities in the PTEN/MMAC1 gene were only detected in 1 of 50 cervical cancers analyzed indicating that aberrant PTEN/MMAC1 function is an uncommon event in the development of cervix cancers. However, similar to studies with the TSG101 gene, screening for aberrant transcripts of PTEN/MMAC1 with nested RT-PCR may detect transcripts, which, although they vary from the normal size, may not be related to oncogenesis as they are also frequently found in normal tissues of the same patient.

Different patterns of serum chromogranin A in patients with prostate cancer with and without undergoing hormonal therapy

Elevated serum chromogranin A (CgA) levels have been detected in patients with prostate cancer who have developed resistance to hormonal therapy. We would like to reexamine these cases by using serial specimens to determine whether such elevated levels are also detectable in prostate cancer patients not undergoing hormonal therapy. Serum CgA was measured in both random and serial specimens from prostate cancer patients with and without undergoing hormonal therapy. We found that serum CgA levels became elevated much earlier than did the levels of serum PSA in approximately one-third of prostate cancer patients developing resistance to hormonal therapy. On the other hand, serum CgA levels became elevated at later, more advanced stages of the disease in patients not undergoing hormonal therapy. Elevated serum CgA levels were usually detected in specimens containing highly elevated PSA. The early rise of serum CgA levels provides an early signal allowing a change of therapy to be made before the disease progresses to a fatal stage. Drugs targeting neuroendocrine cells should be considered for prostate cancer patients with elevated serum CgA levels.

Acute tumour lysis syndrome: a case in AL amyloidosis

Tumour lysis syndrome (TLS) in plasma cell dyscrasias is extremely rare. TLS has been described in eight cases of multiple myeloma undergoing high-dose therapy with autologous stem cell transplant (ASCT). Recently, clinical trials of intensive chemotherapy followed by autologous or allogeneic stem cell support has been shown to offer potential benefit in AL (amyloid light-chain) amyloidosis. TLS in primary AL amyloidosis in this setting has not been previously reported. We report a case of TLS in a patient with AL amyloidosis which developed after high-dose melphalan chemotherapy supported by ASCT.

Differential distribution of apolipoprotein E in young and aged spontaneously hypertensive and stroke-prone rats

OBJECTIVES

To evaluate whether the differential distribution of apolipoprotein E among lipoprotein fractions and hepatic expression of the apolipoprotein E gene are causal factors in the regulation of lipid metabolism and physiological functions in young and aged spontaneously hypertensive and stroke-prone rats.

DESIGN AND METHODS

Biochemical analyses were performed on serum and hepatic specimens from young (2-month-old) and aged (8-month-old) spontaneously hypertensive rats, stroke-prone spontaneously hypertensive rats and normotensive Wistar-Kyoto rats. Levels of apolipoprotein E among various lipoprotein fractions were determined using sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Liver concentrations of apolipoprotein E mRNA were analyzed by Northern blotting and relative levels of apolipoprotein E mRNA in different strains of rats were compared. Statistical analysis was performed by measuring correlations between hepatic apolipoprotein E mRNA levels and biological parameters.

RESULTS

Levels of apolipoprotein E in high-density and low-density lipoproteins were significantly lower in hypertensive rats than in age-matched normotensive Wistar- Kyoto rats. Although there was a significant increase in high-density lipoprotein apolipoprotein E contents in all aged animals, the elevation in aged hypertensive rats was much less than that in aged normotensive rats. Levels of apolipoprotein E in the very-low-density lipoprotein fraction were diminished in young stroke-prone rats but were remarkably high in aged rats. Steady-state levels of apolipoprotein E mRNA increased with age in all strains of rats, whereas aged hypertensive rats exhibited lower apolipoprotein E mRNA levels than aged normotensive rats.

CONCLUSIONS

The distribution of apolipoprotein E among various lipoprotein fractions was dramatically altered with age, and the alteration varied among different strains of rats. The differential distribution of apolipoprotein E in young and aged spontaneously hypertensive and stroke-prone rats suggests that apolipoprotein E could be a causal factor that disturbs the homeostasis of lipids and lipoproteins and perturbs physiological functions in hypertensive rats.

M phase phosphorylation of cytoplasmic dynein intermediate chain and p150(Glued)

To understand how the dramatic cell biological changes of oocyte maturation are brought about, we have begun to identify proteins whose phosphorylation state changes during Xenopus oocyte maturation. Here we have focused on one such protein, p83. We partially purified p83, obtained peptide sequence, and identified it as the intermediate chain of cytoplasmic dynein. During oocyte maturation, dynein intermediate chain became hyperphosphorylated at the time of germinal vesicle breakdown and remained hyperphosphorylated throughout the rest of meiosis and early embryogenesis. p150(Glued), a subunit of dynactin that has been shown to bind to dynein intermediate chain, underwent similar changes in its phosphorylation. Both dynein intermediate chain and p150(Glued) also became hyperphosphorylated during M phase in XTC-2 cells and HeLa cells. Thus, two components of the dynein-dynactin complex undergo coordinated phosphorylation changes at two G2/M transitions (maturation in oocytes and mitosis in cells in culture) but remain constitutively in their M phase forms during early embryogenesis. Dynein intermediate chain and p150(Glued) phosphorylation may positively regulate mitotic processes, such as spindle assembly or orientation, or negatively regulate interphase processes such as minus-end-directed organelle trafficking.

Mutation analysis of the PTEN/MMAC1 gene in cancers of the digestive tract

The 10q23.3 gene PTEN (phosphatase and Tensin homologue deleted on chromosome 10) or MMAC1 (mutated in multiple advanced cancers 1) was recently reported to undergo frequent mutation, including mutations and deletions in multiple advanced cancers. This study showed that the aberrant transcripts of this gene are frequently found in cancers of the digestive tract, paired non-cancerous tissues and normal peripheral mononuclear cells. Sequence analysis of the aberrant transcripts revealed three types of deletions: (i) a deletion junction with a splicing-like donor or acceptor sequence; (ii) several-base homology near or between the donor acceptor site at the deletion junction; and (iii) deletion with insertion. From these results, it is suggested that aberrant transcripts of PTEN/MMAC1 found by nested reverse transcription-polymerase chain reaction are a common (or natural) phenomenon unrelated to oncogenesis. The mechanism producing these aberrant transcripts needs further investigation. Using single-strand conformation polymorphism and direct sequencing to analyse for small base changes of the genomic DNA of the PTEN/MMAC1 gene revealed no point mutations or small base changes.

Oxidation of dichlorvos with hydrogen peroxide using ferrous ion as catalyst

This study examines how Fenton's reagent (Fe2+ and H2O2) decomposed dichlorvos insecticide. Results showed that dichlorvos decomposed in a two-stage reaction. The first stage is a Fe2+/H2O2 reaction in which dichlorvos swiftly decomposed. In the second stage, dichlorvos decomposed somewhat less rapidly, and it is a Fe3+/H2O2 reaction. The detection of ferrous ions also supports the theory of the two-stage reaction for the dichlorvos oxidation with Fenton's reagent. The dissolved oxygen of the solution decreased rapidly in the first stage reaction, but it slowly increased in the second stage with a zero-order kinetics. The Fenton system decomposed dichlorvos most rapidly when the initial pH in the solution is 3-4. In addition, increasing the concentration of hydrogen peroxide or ferrous ions can enhance the decomposition of dichlorvos. Consequently, the relationship of rate constant (kobs), [H2O2] and [Fe2+] at initial pH 3 is determined as kobs = 2.67 x 10(4)[H2O2]0.7[Fe2+]1.2.

Structure of a HoxB1-Pbx1 heterodimer bound to DNA: role of the hexapeptide and a fourth homeodomain helix in complex formation

Hox homeodomain proteins are developmental regulators that determine body plan in a variety of organisms. A majority of the vertebrate Hox proteins bind DNA as heterodimers with the Pbx1 homeodomain protein. We report here the 2.35 A structure of a ternary complex containing a human HoxB1-Pbx1 heterodimer bound to DNA. Heterodimer contacts are mediated by the hexapeptide of HoxB1, which binds in a pocket in the Pbx1 protein formed in part by a three-amino acid insertion in the Pbx1 homeodomain. The Pbx1 DNA-binding domain is larger than the canonical homeodomain, containing an additional alpha helix that appears to contribute to binding of the HoxB1 hexapeptide and to stable binding of Pbx1 to DNA. The structure suggests a model for modulation of Hox DNA binding activity by Pbx1 and related proteins.

Analysis of TSG101 tumour susceptibility gene transcripts in cervical and endometrial cancers

Carcinoma of the uterine cervix is a common malignancy among women that has been found to show loss of heterozygosity in the chromosome 11p. Recent studies have localized the TSG101 gene in this region, and also demonstrated a high frequency of abnormalities of this gene in human breast cancer. To determine the role of the TSG101 gene in the carcinogenesis of cervical and uterine carcinoma, 19 cases of cervical carcinoma and five cases of endometrial carcinoma, as well as nearby non-cancerous tissue from the same patients, and 16 blood samples from healthy persons as normal control were analysed by Southern blot analysis of genomic DNA, reverse transcription of the TSG101 mRNA followed by PCR amplification and sequencing of the products. We found that abnormal transcripts of the TSG101 gene were common both in cancerous or non-cancerous tissues of the uterus and cervix and in normal peripheral mononuclear cells. There was no genomic deletion or rearrangement in spite of the presence of abnormal transcripts, and no definite relationship between the abnormal transcripts and HPV infection was found. Although the frequency of abnormal transcripts was higher in cancerous than in non-cancerous tissue, normal peripheral mononuclear cells also had abnormal transcripts. Given these findings, the role of the TSG101 gene as a tumour-suppressor gene should be re-evaluated. Because some aberrant transcripts could be found at the first PCR reaction, we suggest that the aberrant transcripts might be the result of imperfect minor splicesome products.

A novel protein complex that interacts with the vitamin D3 receptor in a ligand-dependent manner and enhances VDR transactivation in a cell-free system

Nuclear receptors transduce hormonal signals by binding directly to DNA target sites in promoters and modulating the transcription of linked genes. Receptor-mediated transactivation appears to be potentiated in response to ligand by a number of coactivators that may provide key interactions with components of the transcription preinitiation complex and/or alter chromatin structure. Here, we use the vitamin D3 receptor ligand-binding domain (VDR LBD) as an affinity matrix to identify components of a transcriptionally active nuclear extract that interact with VDR in response to ligand. We describe the purification of a complex of at least 10 VDR interacting proteins (DRIPs) ranging from 65 to 250 kD that associate with the receptor in a strictly 1,25-dihydroxyvitamin D3-dependent manner. These proteins also appear to interact with other, but not all, nuclear receptors, such as the thyroid hormone receptor. The DRIPs are distinct from known nuclear receptor coactivators, although like these coactivators, their interaction also requires the AF-2 transactivation motif of VDR. In addition, the DRIP complex contains histone acetyltransferase activity, indicating that at least one or more of the DRIPs may function at the level of nucleosomal modification. However, we show that the DRIPs selectively enhance the transcriptional activity of VDR on a naked DNA template utilizing a cell-free, ligand-dependent transcription assay. Moreover, this activity can be specifically depleted from the extract by liganded, but not unliganded, VDR-LBD. Overexpression of DRIP100 in vivo resulted in a strong squelching of VDR transactivation, suggesting the sequestration of other limiting factors, including components of the DRIP complex. These results demonstrate the existence of a new complex of novel functional nuclear receptor coactivators.

Analysis of FHIT transcripts in cervical and endometrial cancers

Carcinoma of the uterine cervix is a common malignancy, and many affected women, have been found to exhibit loss of heterozygosity (LOH) in the chromosome 3p region. Recent studies have localized the FHIT (fragile histidine triad) gene in this region and also demonstrated a high frequency of abnormalities of this gene in various cancers. To determine the role of the FHIT gene in cervical and uterine carcinomas, 16 cases of cervical carcinoma and 7 cases of endometrial carcinoma, as well as nearby non-cancerous tissues in these patients, were analyzed by reverse transcription of the FHIT mRNA followed by polymerase chain reaction amplification and sequencing of the products. In this study, 13 of 16 cervical cancers and 4 of 7 endometrial cancers displayed abnormal FHIT transcripts, including a lack of 2 or more exons of the FHIT gene, the insertion of several bases in the deletion junctions, and a 282 bp deletion from cDNA 171 to 452, resulting in a frameshift. Moreover, 5 of 16 matched non-cancerous tissues from the cervical cancer patients and 4 of 7 non-cancerous tissues from endometrial cancer patients also showed the presence of abnormal transcripts lacking 3 or more exons of the FHIT gene. Only 1 of 23 paired samples exhibited LOH. Our results suggest that the abnormal transcript of the FHIT gene is common in both normal and tumor tissues of the uterus and cervix. We also checked for HPV infection in these samples and found no definite relationship between the abnormal transcript and human papillomavirus infection.

Rapid detection of a recombinant hotspot associated with Charcot-Marie-Tooth disease type IA duplication by a PCR-based DNA test

A 1.5-Mb duplication on chromosome 17p11.2-p12 (CMT1A duplication) caused by a misalignment of the CMT1A repeat sequences (CMT1A-REPs) is associated with Charcot-Marie-Tooth disease type 1A (CMT1A). A hotspot of crossover breakpoints located in a 3.2-kb region of the CMT1A-REPs accounts for three-quarters of the rearrangements in CMT1A patients. We developed a PCR-based diagnostic method to detect a recombination hotspot associated with the CMT1A duplication. Thirty-one CMT1A Chinese patients from different families and 50 healthy people over 65 years of age were studied. Twenty-seven of the 31 cases demonstrated the 3.2-kb hotspot crossover, of which there were two subgroups. The type 1 crossover breakpoint was located at the distal CMT1A-REP around the PmeI site, and accounted for 24 of the 27 cases with a 3.2-kb hotspot crossover in CMT1A duplication patients. The type 2 crossover breakpoint was located at the distal CMT1A-REP around the base 3625 region, accounting for 3 of the 27 cases. The results correlated very well with the results of Southern transfer analysis. This study has a potentially important role in the diagnosis of CMT1A disease.

Molecular analysis of survival motor neuron (SMN) and neuronal apoptosis inhibitory protein (NAIP) genes of spinal muscular atrophy patients and their parents

We have assayed deletions of two candidate genes for spinal muscular atrophy (SMA), the survival motor neuron (SMN) and neuronal apoptosis inhibitory protein (NAIP) genes, in 101 patients from 86 Chinese SMA families. Deletions of exons 7 and 8 of the telomeric SMN gene were detected in 100%, 78.6%, 96.6%, and 16.7%, in type I, II, III, and adult-onset SMA patients, respectively. Deletion of exon 7 only was found in eight type II and one type III patient. One type II patient did not have a deletion of either exon 7 or 8. The prevalence of deletions of exons 5 and 6 of the NAIP gene were 22.5% and 2.4% in type I and II SMA patients, respectively. We also examined four polymorphisms of SMN genes and found that there were only two, SMN-2 and CBCD541-2, in Chinese subjects. In our study, analysis of the ratio of the telomeric to centromeric portion (T/C ratio) of the SMN gene after enzyme digestion was performed to differentiate carriers, normals, and SMA patients. We found the T/C ratio of exon 7 of the SMN gene differed significantly among the three groups, and may be used for carrier analysis. An asymptomatic individual with homozygous deletion of exons 7 and 8 of the SMN gene showed no difference in microsatellite markers in the SMA-related 5q11.2-5q13.3. In conclusion, SMN deletion in clinically presumed child-onset SMA should be considered as confirmation of the diagnosis. However, adult-onset SMA, a heterogeneous disease with phenotypical similarities to child-onset SMA, may be caused by SMN or other gene(s).

Meis proteins are major in vivo DNA binding partners for wild-type but not chimeric Pbx proteins

The Pbx1 and Meis1 proto-oncogenes code for divergent homeodomain proteins that are targets for oncogenic mutations in human and murine leukemias, respectively, and implicated by genetic analyses to functionally collaborate with Hox proteins during embryonic development and/or oncogenesis. Although Pbx proteins have been shown to dimerize with Hox proteins and modulate their DNA binding properties in vitro, the biochemical compositions of endogenous Pbx-containing complexes have not been determined. In the present study, we demonstrate that Pbx and Meis proteins form abundant complexes that comprise a major Pbx-containing DNA binding activity in nuclear extracts of cultured cells and mouse embryos. Pbx1 and Meis1 dimerize in solution and cooperatively bind bipartite DNA sequences consisting of directly adjacent Pbx and Meis half sites. Pbx1-Meis1 heterodimers display distinctive DNA binding specificities and cross-bind to a subset of Pbx-Hox sites, including those previously implicated as response elements for the execution of Pbx-dependent Hox programs in vivo. Chimeric oncoprotein E2a-Pbx1 is unable to bind DNA with Meis1, due to the deletion of amino-terminal Pbx1 sequences following fusion with E2a. We conclude that Meis proteins are preferred in vivo DNA binding partners for wild-type Pbx1, a relationship that is circumvented by its oncogenic counterpart E2a-Pbx1.

Valtrac-secured intracolonic bypass device: an experimental study

PURPOSE

The intracolonic bypass tube has been used both experimentally and clinically to protect the anastomotic site. A newly designed intracolonic bypass, the Valtrac-secured intracolonic bypass, which consisted of a biofragmentable anastomosis ring (BAR) and was connected with a soft, thin vinyl tube, was used in the colon approximately 5 to 10 cm proximal to the anastomotic site. The distal end of the vinyl tube is passed through the colonic anastomosis to the anus to bypass the fecal stream.

METHODS

Eighteen piglets were divided into three groups of six each. Group A piglets underwent colon resection and rough anastomosis with large gaps between sutures, followed by Valtrac-secured intracolonic bypass. Group B piglets underwent the same procedures, but a colonic outlet obstruction also was done with pursestring sutures tied over the anus. Group C piglets underwent colon resection and rough anastomosis, but no intracolonic bypass tube was inserted (as in the control group).

RESULTS

All Group A and Group B piglets survived. Passage of the BARs occurred approximately two weeks later. As the barium enema passed through the bypass tube, it showed a patent BAR-secured tube and intact anastomosis with no leakage. In Group C, anastomotic leakage occurred in four of six piglets, three of which died. Barium enema showed leakage at the anastomotic site.

CONCLUSIONS

In the animal model we used, our new intracolonic bypass device proved to be a simple, safe, reliable means of protecting the anastomotic site and, thereby, eliminated the need for a diverting colostomy. Still we need further steps to test its potential in clinical use.

Identification and differentiation of bear bile used in medicinal products in Taiwan

One hundred eighty-three suspect bear bile used in medicinal products, collected in Taiwan as gall bladders or dried powder forms, were analyzed using FTIR, HPTLC, and HPLC techniques to identify whether they are indeed bear bile. Those confirmed were further examined to determine whether the observed analytical parameters can be reliably used for source inference, i.e., differentiating products among North American black bear, farmed Asiatic black bear, polar bear, etc. Our data suggested that North American and polar bears contain a higher concentration of TC (relative to TUDC and TCDC), whereas the relative concentration of TC in Asiatic bears (wild or farmed) is much lower. Thus, the relative concentration of TC can potentially be used for differentiating Asiatic bear bile from North American and polar bear products, but it cannot be used for the differentiation of wild and farmed bear bile as suggested in an earlier report by Espinoza et al. The origin of the 183 samples analyzed were found to be as follows: 118 (64%), bile salts, or gall bladders were of domestic pig; 56 (31%), bile products of Asiatic bear; 4 (2.2%), Asiatic bear mixed with pig bile salts; 3 (1.6%) goat gall bladders; 1 (0.55%) water buffalo bile salts; and 1 (0.55%), pig bile salts mixed with water buffalo bile salts.

Chimeric oncoprotein E2a-Pbx1 induces apoptosis of hematopoietic cells by a p53-independent mechanism that is suppressed by Bcl-2

The chimeric oncoprotein E2a-Pbx1 results from fusion of the E2A and PBX1 genes following t(1;19) chromosomal translocations in B cell precursor acute leukemias. Experimentally B cell progenitors do not tolerate constitutive expression of E2a-Pbx1 which contrasts with transformation of several other cell types following its stable expression both in vitro and in vivo. To further investigate the effects of E2a-Pbx1 on the B cell progenitors, we conditionally expressed E2a-Pbx1 under control of a metal response element in hematopoietic precursor cell lines in vitro. Inducible expression of E2a-Pbx1 resulted in cell death with the morphologic and molecular features of apoptosis. A structure-function analysis demonstrated that induction of apoptosis was not a dominant-negative effect of the E2a moiety but, rather, required the DNA-binding homeodomain of Pbx1. E2a-Pbx1-induced apoptosis proceeded through a BCL2-responsive checkpoint eventuating in PARP inactivation but did require p53. Constitutive expression of E2a-Pbx1 did not induce apoptosis or continued cycling of Rat-1 fibroblasts in low serum conditions. These studies demonstrate that E2a-Pbx1 initiates programmed cell death of hematopoietic precursers by a mechanism that requires its chimeric transcriptional properties, but, unlike other nuclear oncoproteins, is independent of p53.

Differential expression of the alpha and beta subunits of the large-conductance calcium-activated potassium channel: implication for channel diversity

In addition to the large alpha subunits that conduct selective ion currents, many native voltage-gated ion channels contain associated proteins which modulate the channel activity. Recently, a beta subunit of the large-conductance calcium-activated K+ (BK) channel has been cloned and functionally characterized. In this report, we studied the tissue distribution of the alpha and beta subunits of rat BK channels by nuclease protection analyses and in situ hybridization. BK alpha mRNA is widely distributed but is especially enriched in the brain. In the adult brain, BK alpha expression is robust and widespread throughout all areas of the neo-, olfactory and hippocampal cortices, habenula and cerebellum. Other prominent sites of BK alpha expression include thalamus and amygdala. In marked contrast to the expression pattern of BK alpha mRNA, the expression of BK beta mRNA is relatively low and preferentially in the periphery. In rat brains, BK beta mRNA occurs only in a few discrete populations of neurons that also express BK alpha messages. These results indicate that the major type of BK channels in the brain, unlike the alpha beta channel type in aortic and tracheal smooth muscle, is devoid of the beta subunit. These observations provide a structural basis for the BK channel diversity observed in a variety of tissues.