Biomedical subjects

Jianxin Zhang

Publications and source records attributed to Jianxin Zhang.

13 recordsLinked to original sources

PubMed2006

Determination of the surface free energy of crystalline and amorphous lactose by atomic force microscopy adhesion measurement.

PURPOSE: This study was conducted to accurately measure the dispersive surface free energy of lactose solids in ordered and disordered states. METHODS: Atomic force microscopy (AFM) was used to determine the contact adhesion force between an AFM tip and lactose under low humidity (ca. 1% RH). The geometry of the tip contacting apex was characterized by scanning a porous aluminum film with ultrasharp spikes (radius 2-3 nm). A sphere vs. flat surface model was employed to relate the adhesion force determined to the surface energy based upon the Johnson-Kendal-Roberts theory. Spray-dried amorphous lactose in a compressed-disk form and single crystals of alpha-lactose monohydrate were prepared as model samples. RESULTS: The condition of the smooth sample surface and sphere-shaped tip used was shown to be appropriate to the application of the JKR model. The surface energy of crystalline [(0,-1,-1) face] and amorphous lactose was determined to be 23.3 +/- 2.3 and 57.4 +/- 7.9 mJ m(-2), respectively. CONCLUSIONS: We have demonstrated the capability of AFM to measure the dispersive surface free energy of pharmaceutical materials directly through a blank probe at the nanometer scale. These data, although consistent with results from more traditional methods, illustrate some unique attributes of this approach, namely, surface energies are directly derived from solid-solid interactions, measurements may be made on specific crystalline faces, and the potential exists to identify the submicron heterogeneity of organic solids in terms of their molecular energy states (such as ordered and disordered lactose).

Algorithms↗

PubMed2005

Identifying and mapping surface amorphous domains.

PURPOSE: Undesirable amorphous material generation during formulation is implicated in a growing number of pharmaceutical problems. Due to the importance of interfacial properties in many drug delivery systems, it seems that surface amorphous material is particularly significant. Consequently, this study investigates a range of methods capable of detecting and mapping surface amorphous material. METHODS: A micron-sized localized surface domain of amorphous sorbitol is generated using a novel localized heating method. The domain is subsequently investigated using atomic force microscopy (AFM) imaging, nanomechanical measurements, and Raman microscopy 3-D profiling. RESULTS: AFM phase and height images reveal nanoscale-order variations within both crystalline and amorphous sorbitol domains. Nanomechanical measurements are able to quantitatively distinguish the amorphous and crystalline domains through local Young's modulus measurements. Raman microscopy also distinguishes the amorphous and crystalline sorbitol through variations in peak width. This is shown to allow mapping of the 3-D distribution of the amorphous phase and is hence complementary to the more surface sensitive AFM measurements. CONCLUSIONS: AFM and Raman microscopy map the distribution of amorphous material at the surface of a sorbitol crystal with submicron spatial resolution, demonstrating surface analysis methods for characterizing semicrystalline solids generated during pharmaceutical processing.

Chemistry, Pharmaceutical↗

PubMed2005

BMP-14 deficiency inhibits long bone fracture healing: a biochemical, histologic, and radiographic assessment.

OBJECTIVES: Bone morphogenetic proteins (BMPs) represent a distinct subset of the transforming growth factor-beta family best known for their role in joint formation and bone growth, and several recent clinical trials have begun to look at their efficacy in the augmentation of fracture healing. The goal of this research is to examine the effect of BMP-14, also known as growth differentiation factor-5 and cartilage- derived morphogenetic protein-1 (GDF-5, CDMP-1) on fracture healing by studying the long bone repair process in mice with a deficiency in this signaling peptide. METHODS: The animal model used for these studies was the BMP-14 (-/-) brachypodism (bp) mouse. Phenotypically normal heterozygous (+/-) littermates were used as controls. Closed mid shaft femur fractures were created and stabilized with intramedullary fixation in 8-week-old female mice. Forty-eight mice per genotype group were examined. On postoperative days 4, 7, 10, 14, 21, 28, 35, and 42, the mice were killed and the femurs and repair tissue were harvested for analysis. At each time point, the fracture sites were analyzed radiographically, histologically, and biochemically. For all quantitative analyses, the data were normalized and analyzed statistically using a 2-factor ANOVA test. RESULTS: Biochemically, peak values of normalized proteoglycan content were approximately 3 times less in the mutant fractures early in the time course of healing compared with the controls (P < 0.05). Histologically, BMP-14-deficient fractures exhibited a delay in peak area cell density, callus organization, and bone formation compared with controls. Radiographic analysis demonstrated that the peak callus was 2 weeks delayed and approximately 2 times less in the mutants compared with controls (P < 0.05). Radiographic grading of callus also demonstrated a significant difference after day 14. CONCLUSIONS: Based on histologic, radiographic, and biochemical analysis, BMP-14-deficient mice display a short-term delay in healing of approximately 1 to 2 weeks. The observed abnormalities seem to be the result of a delay in cellular recruitment and chondrocyte differentiation in the early stages fracture repair in the absence of BMP-14. These results support the hypothesis that BMP-14 deficiency leads to a delay in fracture healing. Further studies are warranted to more closely examine the role of BMP-14 in normal fracture healing and the mechanism by which it works.

Animals↗

PubMed2005

[Developing models on water-saving agriculture through rainwater harvesting for supplemental irrigation in northern China semi-arid region].

Zhungeer of Inner Mongolia, an arsenic-bearing sandstone area of northern Loess Plateau, is one of the sites with most serious soil and water losses in China, while rainwater harvesting (RWH) for supplemental irrigation is the only approach to abate droughts in this region. In the ongoing water saving agriculture project, a national 863 project of China, Zhungeer was chosen as a demonstration zone of water-saving dryland agriculture through rainwater harvesting for supplemental irrigation in northern China semi-arid region. The traditional RWH and utilization lacks of holistic consideration, resulting in the blindness in engineering planning and production arrangement. Based on the analysis of the ecological, economic and societal conditions in the demonstration zone, this paper summarized the technological system of dryland cropping production centered on RWH for supplemental irrigation, and developed three models of RWH and highly effective crop-planting, RWH and ecological pasturing, and domestic RWH and economy. The water demand standards for integrative rainwater utilization in the demonstration zone were determined, and the ecological and socio-economic assessment on the three years implement effects of the models was conducted.

Agriculture↗

PubMed2005

[Determination of chloramphenicol residues in milk by reversed-phase high performance liquid chromatography with fluorescence detection].

A high performance liquid chromatographic method with fluorescence detection for the determination of chloramphenicol (CAP) residues in milk was developed. Although CAP itself is non-fluorescent the aromatic nitro group of CAP could be reduced to aromatic primary amino group and fluorescamine can be used as a selective reagent for primary amines. Therefore, the CAP was derivatized with fluorescamine prior to injection in this project. The HPLC method was performed on a Diamond C18 column (250 mm x 4.6 mm i. d., 4.0 microm) with the mobile phase composed of sodium acetate buffer (0.02 mol/L, pH 6.0) -acetonitrile-tetrahydrofuran (76: 16: 8, v/v/v). The flow rate of the mobile phase was set at 1.0 mL/min, and the column was maintained at 40 degrees C. Analytes were detected by a fluorescence detector at 410 nm excitation and 508 nm emission wavelength. The standard curve was linear in the range from 0.4 microg/L to 800 microg/L. The limit of detection (LOD) was 0.2 microg/L, and the limit of quantitation (LOQ) was 0.4 microg/L. Overall recoveries were between 66.6% and 92.8% with relative standard deviations between 4.5% and 9.4%. The procedure provides a rapid, reliable and sensitive method for the determination of CAP in milk.

Animals↗

PubMed2004

Convergent validity of the Chinese Personality Assessment Inventory and the Minnesota Multiphasic Personality Inventory-2: preliminary findings with a normative sample.

We examined the convergent validity of the Chinese Personality Assessment Inventory (CPAI; Cheung, Leung, et al., 1996), an indigenously constructed measure, by comparing its patterns of correlations with the MMPI-2 (Butcher et al., 2001). A valid sample of 147 Chinese students took both the CPAI and the MMPI-2. Results provide preliminary support for the convergence between most of the CPAI clinical scales and the relevant MMPI-2 scales. The CPAI personality scales further illustrated the patterns of personality features associated with the MMPI-2 scales in a Chinese cultural context. We discuss discrepancies in the correspondence between a number of CPAI and MMPI-2 clinical scales.

Adult↗

PubMed2004

[The observation on the mechanism of speech forming by slit-like trachea-esophagus puncture after total laryngectomy].

OBJECTIVE: To observe the mechanism of the rehabilitated speech using slit-like fistula between trachea and esophagus after total laryngectomy. METHOD: Forty patients after total laryngectomy all come from the fourth central hospital of Tianjin. They all reconstructed voice using slit-like fistula between trachea and esophagus primary or secondary stage. We use teleradiography and laryngotroboscope to observe its mechanism of store gas stage, deliver gas stage and phonation stage. RESULT: While inspiratory, the pulmonary enlarged, and the upper esophagus was closed and circulus invension. After this, the infra-pharyngeal cavity expanded, looks like a downward triangular taper. The upper end of the esophagus opened suddenly. Phonation begin, the superior esophagus was full of air as a ball. The air escape through the segment of trachea-esophagus. The meatus of esophagus opened in coronal position and turn over like lip. It is vibrated together with nearby mucus, mucosa to form voice. After that, thorax shrink, the meatus of esophagus turn in again, the voice behavior is over. CONCLUSION: The power organ of trachea-esophagus voice is lung. It is crucial for the trachea-esophagus fistula unobstructed and smooth to forming voice. When phonation, the mucosa, mucus of infra-pharyngeal and esophageal meatus take part in vibration.

Aged↗

PubMed2003

Determination of the upper limit of vulnerability using implantable cardioverter-defibrillator electrograms.

BACKGROUND: The upper limit of vulnerability (ULV) correlates with the defibrillation threshold and can be determined with 1 episode of ventricular fibrillation (VF). To automate the ULV in an implantable cardioverter-defibrillator (ICD), the most vulnerable intervals must be identified from an ICD electrogram rather than the latest-peaking surface T wave (Tpeak). We hypothesized that the recovery time (TR), defined as the maximum derivative (dV/dt) of the T wave of the shock electrogram, correlates with the most vulnerable intervals. METHODS AND RESULTS: We determined ULV, defibrillation threshold, and the most vulnerable intervals in 25 patients at ICD implantation. The ULV was the weakest T-wave shock that did not induce VF. The most vulnerable intervals were the ones associated with the strongest shocks that induced VF. Telemetered shock electrograms were stored on digital tape and differentiated offline to measure TR. Tpeak and TR were highly correlated (Tpeak-TR=-2+/-11 ms; rho=0.80, P<0.001). At least 1 most vulnerable interval timed between -20 ms and +20 ms relative to Tpeak in all patients and between -40 ms and +20 ms relative to TR in 96% of patients. CONCLUSIONS: The recovery time of shock electrograms provides accurate information about global repolarization. TR closely approximates Tpeak. The ULV method may be automated in an ICD by timing T-wave shocks relative to TR.

Aged↗

PubMed2003

Clinical validation of the Chinese Personality Assessment Inventory.

The clinical validity of the Chinese Personality Assessment Inventory (CPAI; F. M. Cheung, K. Leung, et al., 1996) was examined in 2 studies involving a group of 167 male prisoners in Hong Kong and a group of 339 psychiatric patients in China. Elevated scores on the clinical scales were obtained for the clinical samples. Logistic regression analyses confirmed that the CPAI scales were useful in differentiating between male prisoner and the Hong Kong male normative sample and between psychiatric patients and a random sample of normal adults in China. Multivariate analyses of variance results showed significant differences on the CPAI clinical scales and personality scales among subgroups of psychiatric patients with diagnoses of bipolar, schizophrenic, and neurotic disorders. The usefulness of an indigenous personality inventory is discussed.

Adolescent↗

PubMed2003

Indigenous measures of personality assessment in Asian countries: a review.

This article reviews attempts to develop multidimensional personality measures in Asia and their applications in clinical assessment. Indigenous personality assessment measures in India, Korea, Japan, the Philippines, and Taiwan are examined. These early attempts have not yielded a comprehensive personality measure that integrates a theoretical framework and an empirical program of validation. The Chinese Personality Assessment Inventory (CPAI) is cited as an example to illustrate the process of developing an indigenous measure that meets the testing standards of established assessment instruments. On the basis of the research findings from the CPAI, the authors discuss the relevance of indigenous measures in clinical assessment in native cultures as well as in informing mainstream personality assessment.

Asia↗

PubMed2003

[Study on post-laryngectomy partial laryngeal defect repaired with omohyoid myofascial flap].

OBJECTIVE: To explore the clinical effect on defect of post-laryngectomy partial laryngeal repaired with omohyoid myofascial flap. METHOD: Twenty-four cases of supraglottic and glottic cancer were treated surgically. The tumors and involved cartilages were removed entirely. The omohyoid myofascial flap was utilized to repair the defects of larynx and reconstruct the glottis. For the cases of unilateral fixation of arytenoid, the arytenoids were removed and replaced by a piece of omohyoideus linked to hyoid bone, then were covered with mucous. The cases above T2 supraglottic and T3 glottic received radiotherapy. RESULT: The following-up time is 1-5 years. One case of supraglottic cancer(T3) dies from local recurrence after operation for 2 years and 9 months. One case of glottic cancer(T3) dies from neck and bone metastasis after operation for 4 years and 3 months. Swallow function was preserved in all cases. The rate of deconnalation was 95.8%. 91.7% patients had laryngeal functions restored. CONCLUSION: For selected cases, using omohyoid myofascial flap to repair the partial laryngeal defect and reconstruct glottis is available and practicable.

Aged↗

PubMed2002

Differential scanning calorimetry and scanning thermal microscopy analysis of pharmaceutical materials.

Micro-thermal analysis (microTA) by scanning thermal microscopy is being used increasingly for the analysis of pharmaceutical dosage forms. However, there is currently little evidence to show that microTA data can compare directly with that from the established approach of differential scanning calorimetry (DSC). This work compares DSC and microTA data from an active vitamin B6 analogue, pyridoxal hydrochloride, and two commonly used pharmaceutical excipients, Mannitol and Avicel which are used in its formulation. It is found that microTA provides precise and accurate micro-thermal analytical data with 0.1 K thermal sensitivity, which is comparable to that obtained by DSC measurements of bulk samples. It is also shown that microTA offers the opportunity to study single particles and the interfacial region between particles, data which is currently inaccessible through the DSC technique.

Calorimetry, Differential Scanning↗

PubMed2002

Discrimination of ventricular tachycardia from supraventricular tachycardia by a downloaded wavelet-transform morphology algorithm: a paradigm for development of implantable cardioverter defibrillator detection algorithms.

INTRODUCTION: Present implantable cardioverter defibrillators (ICDs) have algorithms that discriminate supraventricular tachycardia (SVT) from ventricular tachycardia (VT). One type of algorithm is based on differences in morphology of ventricular electrograms during VT and SVT. Prior SVT-VT discrimination algorithms have not undergone real-time evaluation in ambulatory patients until they were incorporated permanently into ICDs. This approach may result in incomplete testing of electrogram morphology algorithms because they are influenced by posture, activity, and electrogram maturation. We downloaded software into implanted ICDs to study a novel algorithm that compares morphologies of baseline and tachycardia electrograms based on differences between corresponding coefficients of their wavelet transforms. This comparison is expressed as a match-percent score. METHODS AND RESULTS: In 23 patients, we downloaded the wavelet algorithm into implanted ICDs to assess the temporal and postural stability of baseline electrograms as measured by this algorithm and its accuracy for SVT-VT discrimination. Median follow-up was 6 months. Software was downloaded into all ICDs without altering other device functions. With few exceptions, percent template match in baseline rhythm was stable with changes in body position, rest versus walking, isometric exercise, and over time (1 and 3 months). Using the nominal match-percent threshold of 70%, sensitivity for detection of 38 VTs was 100%. Specificity for rejection of 65 SVTs was 78%. SVTs were rejected for a total of 2.7 hours. Inappropriate detections of SVT as VT were caused by electrogram truncation, myopotential interference with low-amplitude electrograms, waveform alignment error, and rate-dependent aberrancy. The first three accounted for 69% of inappropriate detections and could have been prevented by optimal programming. The optimal match-percent threshold was 60% to 70% based on a receiver-operator characteristic curve. After shocks, the median time for baseline electrogram morphology to normalize was 85 seconds. CONCLUSION: The wavelet morphology algorithm has high sensitivity for VT detection. Inappropriate detections of SVT as VT may be reduced by optimal programming. Downloadable software permits evaluation of new algorithms in implanted ICDs.

Aged↗