The Hippocampal Subfield Volume Reduction and Plasma Biomarker Changes in Mild Cognitive Impairment and Alzheimer's Disease

Background

The hippocampus consists of histologically and functionally distinct subfields, which shows differential vulnerabilities to Alzheimer's disease (AD)-associated pathological changes.

Objective

To investigate the atrophy patterns of the main hippocampal subfields in patients with mild cognitive impairment (MCI) and AD and the relationships among the hippocampal subfield volumes, plasma biomarkers and cognitive performance.

Methods

This cross-sectional study included 119 patients stratified into three categories: normal cognition (CN; N = 40), MCI (N = 39), and AD (N = 40). AD-related plasma biomarkers were measured, including amyloid-β (Aβ)42, Aβ40, Aβ42/Aβ40 ratio, p-tau181, and p-tau217, and the hippocampal subfield volumes were calculated using automated segmentation and volumetric procedures implemented in FreeSurfer.

Results

The subiculum body, cornu ammonis (CA) 1-head, CA1-body, CA4-body, molecular_layer_HP-head, molecular_layer_HP-body, and GC-ML-DG-body volumes were smaller in the MCI group than in the CN group. The subiculum body and CA1-body volumes accurately distinguished MCI from CN (area under the curve [AUC] = 0.647-0.657). The subiculum-body, GC-ML-DG-body, CA4-body, and molecular_layer_HP-body volumes accurately distinguished AD from MCI (AUC = 0.822-0.833) and AD from CN (AUC = 0.903-0.905). The p-tau 217 level served as the best plasma indicator of AD and correlated with broader hippocampal subfield volumes. Moreover, mediation analysis demonstrated that the subiculum-body volume mediated the associations between the p-tau217 and p-tau181 levels, and the Montreal Cognitive Assessment and Auditory Verbal Learning Test recognition scores.

Conclusions

Hippocampal subfields with distinctive atrophy patterns may mediate the effects of tau pathology on cognitive function. The subiculum-body may be the most clinically meaningful hippocampal subfield, which could be an effective target region for assessing disease progression.

The effect of icariin on bone metabolism and its potential clinical application

Osteoporosis is a bone disease characterized by reduced bone mass, which leads to increased risk of bone fractures, and poses a significant risk to public health, especially in the elderly population. The traditional Chinese medicinal herb Epimedii has been utilized for centuries to treat bone fracture and bone loss. Icariin is a prenylated flavonol glycoside isolated from Epimedium herb, and has been shown to be the main bioactive component. This review provides a comprehensive survey of previous studies on icariin, including its structure and function, effect on bone metabolism, and potential for clinical application. These studies show that icariin promotes bone formation by stimulating osteogenic differentiation of BMSCs (bone marrow-derived mesenchymal stem cells), while inhibiting osteoclastogenic differentiation and the bone resorption activity of osteoclasts. Furthermore, icariin has been shown to be more potent than other flavonoid compounds in promoting osteogenic differentiation and maturation of osteoblasts. A 24-month randomized double-blind placebo-controlled clinical trial reported that icariin was effective in preventing postmenopausal osteoporosis with relatively low side effects. In conclusion, icariin may represent a class of flavonoids with bone-promoting activity, which could be used as potential treatment of postmenopausal osteoporosis.

A new variable for SRS plan quality evaluation based on normal tissue sparing: the effect of prescription isodose levels

OBJECTIVE

A new dosimetric variable, dose-dropping speed (DDS), was proposed and used to evaluate normal tissue sparing among stereotactic radiosurgery (SRS) plans with different prescription isodose lines.

METHODS

40 plans were generated for 8 intracranial SRS cases, prescribing to isodose levels (IDLs) ranging from 50% to 90% in 10% increments. Whilst maintaining similar coverage and conformity, plans at different IDLs were evaluated in terms of normal tissue sparing using the proposed DDS. The DDS was defined as the greater decay coefficient in a double exponential decay fit of the dose drop-off outside the planning target volume (PTV), which models the steep portion of the drop-off. Provided that the prescription dose covers the whole PTV, a greater DDS indicates better normal tissue sparing.

RESULTS

Among all plans, the DDS was found to be the lowest for the prescription at 90% IDL and the highest for the prescription at 60% or 70%. The beam profile slope change in the penumbra and its field size dependence were explored and given as the physical basis of the findings.

CONCLUSION

A variable was proposed for SRS plan quality evaluation. Using this measure, prescriptions at 60% and 70% IDLs were found to provide best normal tissue sparing.

ADVANCES IN KNOWLEDGE

A new variable was proposed based on which normal tissue sparing was quantitatively evaluated, comparing different prescription IDLs in SRS.

Genetic diversity and relationships among different tomato varieties revealed by EST-SSR markers

The genetic diversity and relationship of 42 tomato varieties sourced from different geographic regions was examined with EST-SSR markers. The genetic diversity was between 0.18 and 0.77, with a mean of 0.49; the polymorphic information content ranged from 0.17 to 0.74, with a mean of 0.45. This indicates a fairly high degree of diversity among these tomato varieties. Based on the cluster analysis using unweighted pair-group method with arithmetic average (UPGMA), all the tomato varieties fell into 5 groups, with no obvious geographical distribution characteristics despite their diverse sources. The principal component analysis (PCA) supported the clustering result; however, relationships among varieties were more complex in the PCA scatterplot than in the UPGMA dendrogram. This information about the genetic relationships between these tomato lines helps distinguish these 42 varieties and will be useful for tomato variety breeding and selection. We confirm that the EST-SSR marker system is useful for studying genetic diversity among tomato varieties. The high degree of polymorphism and the large number of bands obtained per assay shows that SSR is the most informative marker system for tomato genotyping for purposes of rights/protection and for the tomato industry in general. It is recommended that these varieties be subjected to identification using an SSR-based manual cultivar identification diagram strategy or other easy-to-use and referable methods so as to provide a complete set of information concerning genetic relationships and a readily usable means of identifying these varieties.

Antitumor Activity of Tiazofurin in Human Colon Carcinoma HT-29

Tiazofurin is effective in treating end-stage leukemic patients (Tricot et al., Cancer Res 49:3696-3701, 1989). In sensitive tumors, the active metabolite of tiazofurin, TAD, potently inhibits IMP dehydrogenase activity, resulting in reduced guanylate pools. To elucidate tiazofurin activity in human solid tumors, we examined its activity in human colon carcinoma HT-29. Tiazofurin exhibited an LC50 of 35 microM in cultured HT-29 cells. Incubation of HT-29 cells with 100 microM tiazofurin for 2 h resulted in TAD formation (9.3 nmol/g cells) and in a 64% decrease in GTP pools. For biochemical and chemotherapy studies, athymic nude mice were transplanted s.c. with HT-29 cells. Twenty-four days later, mice were injected i.p. with tiazofurin (500 mg/kg); 6 h later, tumors were removed and analyzed. These tumors formed 17 nmol/g of TAD with decreased GTP pools (56%). To study oncolytic activity, transplanted mice were treated 24 h later with tiazofurin (500 mg/kg, once a day for 10 days). To examine the effectiveness of tiazofurin in established tumors, the drug was administered to mice 14 days after tumor implantation (500 mg/kg, once a day for 5 days, course repeated 4 times with a 10-day rest). Both treatment schedules resulted in significant antitumor activity. This study illustrates the potential usefulness of tiazofurin in treating human colon carcinoma.

The Drosophila homolog of the human tumor suppressor gene BHD interacts with the JAK-STAT and Dpp signaling pathways in regulating male germline stem cell maintenance

Birt-Hogg-Dubé syndrome (BHD) is a rare, inherited genodermatosis characterized by hair follicle hamartomas, kidney tumors and spontaneous pneumothorax. The BHD locus was mapped to chromosome 17p11.2 by linkage analysis, and germline mutations in a novel gene (BHD) were identified in a panel of BHD families. Using RNA interference to decrease expression of the Drosophila BHD homolog (DBHD), we have demonstrated that DBHD is required for male germline stem cell (GSC) maintenance in the fly testis. Reduction of DBHD gene activity suppresses the GSC overproliferation phenotype associated with overexpression of either unpaired (upd) or decapentaplegic (dpp). Further genetic interaction experiments suggest that DBHD regulates GSC maintenance downstream or in parallel of the JAK/STAT and Dpp signal-transduction pathways. These findings suggest that the BHD protein may regulate tumorigenesis through modulating stem cells in human.

Dose volume histogram comparison between ADAC Pinnacle and Nomos Corvus systems for IMRT

This paper compares dose volume histograms (DVHs) generated by the ADAC Pinnacle and the Nomos Corvus planning systems. Seven prostate cases and seven head and neck cases were selected for review. Plans computed on both systems possessed exactly the same anatomical contours and IMRT segments. The Pinnacle system used the collapsed cone convolution superposition, while Corvus employed a finite size pencil beam (FSPB) convolution. Prostate DVH results demonstrated similar DVH curves from both systems. For each structure, the ratio of Pinnacle dose value divided by Corvus value was calculated. The high dose structures (which might contain tumour) had ratios close to unity, while the low dose structures (the critical organs) had ratios farther away from unity. Almost all ratios were less than unity, indicating a systematic difference that Pinnacle calculated doses were lower than Corvus ones. Head and neck data provided similar findings. A possible cause for this discrepancy could be the beam modelling. The difference in DVH parameters that we discovered between the two systems was about the same order of magnitude as the measurement-computation difference. When low dose is critical, such difference may affect the clinical planning decision.

Giant-cell tumour of bone. The long-term results of treatment by curettage and bone graft

Giant-cell tumour of bone (GCT) is a locally benign aggressive tumour. The use of adjuvant agents, such as phenol or liquid nitrogen has been recommended to destroy the remaining tumour cells after curettage, and filling of the defect with methylmethacrylate cement has been advocated. Between 1957 and 1992 we treated 92 patients with a GCT with 50% aqueous zinc chloride solution and bone grafting. Their mean age at the time of surgery was 31 years (15 to 59) and the mean follow-up was 11 years (5 to 31). Twelve (13%) had a local recurrence and one had a wound infection. Two developed degenerative changes around the knee. Eighty-six (93%) achieved good or excellent function. Three had moderate function, and three needed amputation. Our findings indicate that treatment with an aqueous solution of zinc chloride and reconstructive bone grafting after curettage gives good results.

Leaf sequencing techniques for MLC-based IMRT

The nonuniform fields required by intensity-modulation radiation therapy (IMRT) can be delivered using conventional multileaf collimators (MLC) as beam modulators. In MLC-based IMRT, the nonuniform field is initially converted into an intensity map represented as a matrix of beam intensities. The intensity map is then decomposed into a series of subfields or segments of uniform intensities. Although there are many ways of segmenting the beam intensity matrix, a resulting subfield is only deliverable if it satisfies the constraints imposed by the MLC. These constraints exist as a result of the design of the MLC. The simplest constraint of the MLC is that its pairs of leaves can only move in and out in one dimension. Additional constraints include collision of opposing leaves and the need to match the tongue-and-groove to reduce interleaf leakage. The practical aspect of MLC-based IMRT requires that an optimized algorithm decomposes the nonuniform field into the least number of segments and therefore reduces the delivery time. This paper examines the static use and the dynamic use of MLCs to perform MLC-based IMRT.

Commissioning and quality assurance for MLC-based IMRT

The commissioning and quality assurance (QA) associated with the implementation of linear accelerator multileaf collimator (MLC)-based intensity-modulated radiation therapy (IMRT) at the University of Nebraska Medical Center are described. Our MLC-based IMRT is implemented using the PRIMUS linear accelerator interface through the IMPAC record and verification system to the CORVUS treatment planning system. The "step-and-shoot" technique is used for this MLC-based IMRT. Commissioning process requires the verification of predefined parameters available on the CORVUS and the collection of some machine data. The machine data required are output factor in air and output factor in phantom, and percent depth dose for a number of field sizes. In addition, inplane and crossplane dose profiles of 4 x 4 cm and 20 x 20 cm field sizes and diagonal dose profiles of a large field size have to be measured. Validation of connectivity and dose model includes the use of uniform intensity bar strips, triangular-shaped nonuniform intensity bar strip, and N-shaped target. QA procedure follows the recommendation of the AAPM Task Group No. 40 report. In addition, the leaf position accuracy and reproducibility of the MLC should be checked at regular intervals. The dose validation is implemented through the hybrid plan where the patient beam parameters are applied to a flat phantom. Independent dose calculation method is used to confirm the dose delivery plan and data input to the CORVUS.

Commissioning of Peacock System for intensity-modulated radiation therapy

The Peacock System was introduced to perform tomographic intensity-modulated radiation therapy (IMRT). Commissioning of the Peacock System included the alignment of the multileaf intensity-modulating collimator (MIMiC) to the beam axis, the alignment of the RTA device for immobilization, and checking the integrity of the CRANE for indexing the treatment couch. In addition, the secondary jaw settings, couch step size, and transmission through the leaves were determined. The dosimetric data required for the CORVUS planning system were divided into linear accelerator-specific and MIMiC-specific. The linear accelerator-specific dosimetric data were relative output in air, relative output in phantom, percent depth dose for a range of field sizes, and diagonal dose profiles for a large field size. The MIMiC-specific dosimetric data were the in-plane and cross-plane dose profiles of a small and a large field size to derive the penumbra fit. For each treatment unit, the Beam Utility software requires the data be entered into the CORVUS planning system in modular forms. These modules were treatment unit information, angle definition, configuration, gantry and couch angles range, dosimetry, results, and verification plans. After the appropriate machine data were entered, CORVUS created a dose model. The dose model was used to create known simple dose distribution for evaluation using the verification tools of the CORVUS. The planned doses for phantoms were confirmed using an ion chamber for point dose measurement and film for relative dose measurement. The planning system calibration factor was initially set at 1.0 and will be changed after data on clinical cases are acquired. The treatment unit was released for clinical use after the approval icon was checked in the verification plans module.

Viewpoints to consider in the development of MLC and IMRT programs

Operational and administrative considerations for the development and implementation of either multileaf collimation (MLC) or non-MLC-based intensity-modulated radiation therapy (IMRT) will be discussed with respect to the impact that this will have on a radiation oncology department. The methodologies that are used in the development process will be reviewed in both the operational and administrative components. Operational issues addressing the potential clinical impact the department will experience, along with the beneficial outcome for the patients, will be major points in this review process. Administrative considerations generally focus on the financial impact that the department and hospital will have to deal with in determining cost benefits of this capital expenditure. This overview will focus on some key discussion points with the incorporation of MLC and IMRT into a radiation oncology department treatment program.

Quality assurance procedures for the Peacock system

The Peacock system is the product of technological innovations that are changing the practice of radiotherapy. It uses dynamic beam modulation technique and inverse planning algorithm, both of which are new methodologies, to perform intensity-modulation radiation therapy (IMRT). The quality assurance (QA) procedure established by Task Group No. 40 did not adequately consider these emerging modalities. A review of literature indicates that published articles on QA procedures concentrate primarily on the verification of dose delivered to phantom during commissioning of the system and dose delivered to phantom before treating patients. Absolute dose measurements using ion chambers and relative dose measurements using film dosimetry have been used to verify delivered doses. QA on equipment performance and equipment safety is limited. This paper will discuss QA on equipment performance, equipment safety, and patient setup reproducibility.

National survey of head and neck verrucous carcinoma: patterns of presentation, care, and outcome

BACKGROUND

Verrucous carcinoma is distinguished by controversy regarding appropriate diagnosis and treatment. This study provides a contemporary survey of demographics, patterns of care, and outcome for this disease in the United States.

METHODS

The National Cancer Data Base had 2350 cases of verrucous carcinoma of the head and neck diagnosed between 1985 and 1996. Statistical procedures included chi-square analyses, Student t tests, and relative survival.

RESULTS

Tumors originated most frequently in the oral cavity (55.9%) and larynx (35.2%). Although most patients were male (60.0%), oral cavity tumors were more common among older females. The most prevalent treatment was surgery alone (69.7%), followed by surgery combined with irradiation (11.0%) and irradiation alone (10.3%). For oral cavity tumors, surgery alone was more common among early (85.8%) than advanced cases (56.9%); a larger proportion of advanced disease received radiation alone or surgery and irradiation combined. Most laryngeal tumors were treated with surgery (60.3% for early and 55.6% for advanced disease), but a higher proportion received radiation alone or surgery combined with radiation compared with oral cavity cases. Five-year relative survival was 77.9%. For localized disease, survival after surgery was 88.9% compared with 57.6% after irradiation.

CONCLUSIONS

Demographic differences implicate different mechanisms of carcinogenesis for verrucous carcinoma arising in the oral cavity and the larynx. Although selection bias may account for the differences observed, patients receiving initial treatment with surgery had better survival than those treated with irradiation, especially for cases originating in the oral cavity.

Analysis of mono- and oligosaccharides by multiwavelength surface plasmon resonance (SPR) spectroscopy

Surface plasmon resonance (SPR) spectra of different saccharides were collected using a home-made multiwavelength SPR apparatus. Pentoses, hexoses, disaccharides and a trisaccharide were distinguished from one another according to their SPR spectra collected at the same concentration. The spectra were also used for the quantitation of sugars by exploring the linear relationship between resonance wavelength and solute concentration. The dynamic linear ranges for the determination of glucose, sucrose and raffinose are 0.01-0.2, 0.005-0.1 and 0.0025-0.1 mol/L, respectively. The SPR spectrum of a mixture of two components was investigated. While the experiments have not been carried out, the implications from this work are that the technique would be applicable to mixtures containing more than two components.

Esthesioneuroblastoma: the University of Iowa experience 1978-1998

OBJECTIVE

Esthesioneuroblastoma is rare and the best treatment has yet to be defined. The purpose of this study is to analyze the natural history, treatment, and patterns of failure of esthesioneuroblastoma treated at one institution.

METHODS

Between 1978 and 1998, 13 patients with esthesioneuroblastoma were identified using the University of Iowa Tumor Registry. All patients were staged according to Kadish criteria. Mean follow-up was 6.3 years. Six patients had 5 or more years of follow-up and four had follow-up exceeding 9.5 years. One patient was lost to follow-up at 36 months.

RESULTS

No patients had Kadish stage A disease, five were stage B, and eight stage C. Overall actuarial 5- and 10-year survival rate was 61% and 24%, respectively. Disease-free survival rate at 5 and 10 years was 56% and 42%, respectively. Seven patients have died, three of intercurrent disease and three of disease progression, one with an unknown disease status. Six patients remain alive, three without evidence of disease and three have experienced a local or regional recurrence. Five patients who were initially controlled developed recurrence, three local only, one locoregional, and one regional and distant. Median time to failure was 96 months. All patients with follow-up exceeding 12 years have experienced either a local or regional recurrence. Survival after salvage therapy in these patients ranged from 3 to 12 years.

CONCLUSION

Esthesioneuroblastoma has a long natural history characterized by frequent local or regional recurrence after conventional treatment. Successful retreatment can lead to prolonged survival.