Biomedical subjects
Publications and source records attributed to W J Yang.
A molt-inhibiting hormone (Prc-MIH) was isolated from the sinus glands of the American crayfish, Procambarus clarkii, and its amino acid sequence was determined. It comprised 75 amino acid residues and had an amidated carboxyl terminus. The amino acid sequence was much more similar to MIH of the shore crab (Cam-MIH) than to MIH of the American lobster (Hoa-MIH).
In order to prolong shelf-life and improve the quality of the vaccine product, not only an effective stabilizer but also a more proper dosage form has been sought. The stability of a Japanese encephalitis (JE) vaccine produced from mouse brain along with a variety of stabilizers and lyophilization protocols was evaluated. Without any stabilizers added, almost 90% of the antigenicity would vanish after freeze-drying process. Comparative studies of various compounds, including carbohydrates, amino acids, peptides and medium 199, on both antigenicity preservation and thermostability of the vaccine were carried out. The results indicated that the best reconstituted vaccines were prepared with two stabilizer formulations, sucrose and sucrose/gelatin. They were further examined by accelerated stability test at room and higher temperatures. The sucrose-added lyophilized vaccine can retain its original antigenicity for more than 60 days both at 37 degrees C and 45 degrees C. We conclude the thermostability efficiency of each of the stabilizers tested is as that follows: sucrose > sucrose/gelatin > gelatin/medium > gelatin.
A series of near-isogenic glycinebetaine-containing and -deficient F8 pairs of Zea mays L. (maize) lines were developed. The pairs of lines differ for alternative alleles of a single locus; the wild-type allele conferring glycinebetaine accumulation is designated Bet1 and the mutant (recessive) allele is designated bet1. The near-isogenic lines were used to investigate whether glycinebetaine deficiency affects the pool size of the glycinebetaine precursor, choline, using a new method for glycinebetaine and choline determination: stable isotope dilution plasma desorption mass spectrometry. Glycinebetaine deficiency in maize was associated with a significant expansion of the free choline pool, but the difference in choline pool size was not equal to the difference in glycinebetaine pool size, suggesting that choline must down-regulate its own synthesis. Consistent with this, glycinebetaine deficiency was also associated with the accumulation of the choline precursor, serine. A randomly amplified polymorphic DNA marker was identified that detects the bet1 allele. In 62 F8 families tested the 10-mer primer 5'-GTCCTCGTAG produced a 1.2-kb polymerase chain reaction product only when DNA from Bet1/bet1 or bet1/bet1 lines was used as template. All 26 homozygous Bet1/Bet1 F8 families tested were null for this marker.
A successful epididymal sperm aspiration, in vitro fertilization and embryo transfer in a woman whose husband had previously undergone extensive attempts at recanalization of the spermatic ducts is reported. A twin pregnancy was achieved using sperm obtained from the husband's epididymal caput. This case demonstrates that pregnancy can be achieved by this reproductive technique in cases of obstructive azoospermia, even after extensive surgery.
Current mathematical models for describing pulse propagation in arteries are summarized. These models include the effects of viscoelasticity, frequency dependent friction, and other factors. One factor that has not been previously considered is the effect of distributed flow leakage. This leakage is known to have a significant effect on pulse propagation in rigid tubes and it has been assumed to have a similar effect in compliant tubes. These effects are described here, along with the results of a recent study by these authors on the effects of the distributed flow leakage in compliant tubes.
Ten patients with SDAT received the ECP therapy. The examination of Hasegawa's Dementia Scale (HDS), single photor emission computed tomography (SPECT) brain imaging, and some biochemical parameters in blood and CSF were selected to evaluate the effect of ECP for SDAT. After ECP treatment, the average HDS score of the patients increased, the value of P was close to 0.05; and the cortical cerebellar ratios of SPECT brain scan, the superoxide dismutase (SOD) activity and the concentrations of somatostatin-like immunoreactivity (SLI), dynorphin AL-13 (Dyn Al-13) in blood and/or CSF were significantly elevated. The results indicated that ECP could not only improve cerebral blood flow, but also make a notable impact on biological active substances in blood and CSF. It is suggested that ECP is beneficial to SDAT patients.
A two-dimensional numerical model was developed to determine the effect of the non-Newtonian behavior of blood on a pulsatile flow at the aortic bifurcation. The blood rheology was described by a weak-form Casson equation. The successive-over-relaxation (SOR) method was used to solve both the vorticity and Poisson equations numerically. It was disclosed that the non-Newtonian property of blood did not drastically change the flow patterns, but caused an appreciable increase in the shear stresses and a slightly higher resistance to both flow separations and the phase shifts between flow layers.
Explore the source record for details and available documents.
To understand the role of fluid dynamics in atherogenesis, especially the effect of the flexibility of arteries, a two-dimensional numerical model for blood flow at the aortic bifurcation with linear viscoelastic walls is developed. The arbitrary Lagrangian-Eulerian method is adopted to deal with the moving boundary problem. The wall expansion induces flow reversals or eddies during the decelerating systole while the wall contraction restricts them during the diastole. A flexible bifurcation experiences the shear stresses about 10 percent lower than those of a rigid one.
Lung abscess was successfully treated with percutaneous drainage in 5 of 6 patients. Complete abscess resolution occurred in 4 patients, partial resolution in one, and no response in one. The duration of drainage ranged from 7 to 18 days (mean 15.5 days) in successful cases. The failure of drainage in one neurologically impaired patient was attributed to persistent aspiration. In 2 patients, concurrent pleural empyema was also cured. CT provided the anatomic details necessary for choosing the puncture site and avoiding puncture of the lung parenchyma. Percutaneous catheter drainage is a safe and effective method for treating lung abscess.
Explore the source record for details and available documents.
Hemodynamics has long been suspected of being involved in arterial diseases, e.g., atherosclerosis. Seemingly good correlation between the atherosclerosis localization and the flow disturbance around bends and bifurcations in large arteries has prompted many studies of blood flow around those regions. This article reviews and critiques biofluid studies at various arterial bifurcations. Both experimental and theoretical models vary greatly in the major assumptions and parameters. The issues discussed include: possible errors from two-dimensional models, the validity of steady flow studies, the existence and influence of the secondary flow, effects of non-Newtonian blood rheology, influences from arterial wall distensibility, effects of the Reynolds number, effects of the area ratio, effects of the Womersley number, effects of corner curvatures, effects of bifurcation angle, errors in the measurement and calculation of wall shear rate, and the possible existence of turbulence.
Thermography is a noninvasive technique through which temperatures are monitored and recorded, thereby allowing visualization of heat flow. There are three types of thermography: liquid crystal thermography (LCT), infrared thermography (IRT) and microwave thermography (MWT). This paper presents a survey of the literature pertinent to the biomedical applications of these types of thermography. The noninvasive and high resolution characteristics of the thermographic systems make them valuable diagnostic as well as therapeutic aids. Typical research areas include detection of blood flow, diagnosis of joint inflammation and cancer, thermal modeling of various body parts, and use in reproductive problems. The survey discloses that thermography has found applications in various fields in medicine, veterinary medicine, pharmacy, and dentistry.
Phytase (myo-inositol hexakisphosphate phosphohydrolase; EC 3.1.3.8 or 3.1.3.26) was purified from rat intestinal mucosa. The purified enzyme preparation exhibited two protein bands on SDS-polyacrylamide gel electrophoresis with estimated molecular masses of 70 kDa and 90 kDa. Rabbit antisera prepared against the 90K subunit cross-reacted with the 70K subunit on immunoblotting. The peptide maps of the 70K and 90K subunits were similar, and the N-terminal amino acid sequences of the two subunit proteins were almost identical. Treatments to remove sugar moieties from the proteins showed that the two subunit proteins had different oligosaccharide chains, although the difference in their molecular masses was not due to the difference in their oligosaccharide compositions. The purified enzyme also showed activity of alkaline phosphatase (orthophosphoric monoester phosphohydrolase; EC 3.1.3.1), but the properties of the two enzyme activities were different; the optimum pH for phytase activity was 7.5, while that for alkaline phosphatase was 10.4. Phytase activity did not necessarily require divalent cations, while Mg2+ was essential for alkaline phosphatase activity. Phenylalanine, a specific inhibitor of intestine-type alkaline phosphatase had no effect on the phytase activity.
The activities of phytase and alkaline phosphatase in the intestine gradually increased in parallel during development of rats, but the 70K and 90K subunits were expressed differentially; only the 70K subunit was detected at birth, whereas the 90K subunit appeared at the weaning period (3 weeks after birth). When rats were forced to wean at 18 days old and fed laboratory chow, the enzyme activity increased markedly and the 90K subunit appeared within 1 day. These findings suggest that weaning is involved in the change in the subunit composition. Increases in the enzyme activity and amount of the 90K subunit were significantly delayed by feeding weanling animals on casein diet, but induced significantly by feeding them on casein diet supplemented with phytate. Thus induction of the 90K subunit seems to be accelerated by intake of phytic acid in the diet. The Km value of the enzyme from suckling rats for phytate was 5.25 mM, while that of adult rats was 0.213 mM. In contrast, the Km value for p-nitrophenyl phosphate (PNPP) was constant during development. The phytase activity of suckling rats did not show a distinct pH-dependence. These findings suggest that the 90K subunit may play some important roles in expressing an efficient phytase activity.
Maize (Zea mays L.) is a betaine-accumulating species, but certain maize genotypes lack betaine almost completely; a single recessive gene has been implicated as the cause of this deficiency (D Rhodes, PJ Rich [1988] Plant Physiol 88: 102-108). This study was undertaken to determine whether betaine deficiency in diverse maize germplasm is conditioned by the same genetic locus, and to define the biochemical lesion(s) involved. Complementation tests indicated that all 13 deficient genotypes tested shared a common locus. One maize population (P77) was found to be segregating for betaine deficiency, and true breeding individuals were used to produce related lines with and without betaine. Leaf tissue of both betaine-positive and betaine-deficient lines readily converted supplied betaine aldehyde to betaine, but only the betaine-containing line was able to oxidize supplied choline to betaine. This locates the lesion in betaine-deficient plants at the choline --> betaine aldehyde step of betaine synthesis. Consistent with this location, betaine-deficient plants were shown to have no detectable endogenous pool of betaine aldehyde.
Leaf tissue of alfalfa (Medicago sativa L.) was found to contain prolinebetaine, pipecolatebetaine, hydroxyprolinebetaine, and glycinebetaine. As n-butyl esters, these chemical species exhibit molecular cations at mass/charge ratio (m/z) 200, 214, 216, and 174, respectively, when analyzed by fast atom bombardment mass spectrometry. The underivatized betaines exhibit protonated molecular ions at m/z 144, 158, 160, and 118, respectively, when analyzed by desorption chemical ionization mass spectrometry. Extensive (>45-fold) genotypic variation for hydroxyprolinebetaine level was identified in alfalfa. Because a significant inverse correlation between prolinebetaine and hydroxyprolinebetaine levels was observed among 15 alfalfa genotypes evaluated, it is possible that these compounds may be derived from a common intermediate. Birdsfoot trefoil (Lotus corniculatus L.) contained prolinebetaine, but only traces of glycinebetaine, pipecolatebetaine, and hydroxyprolinebetaine. Red clover (Trifolium pratense L.) lacked prolinebetaine, pipecolatebetaine, and hydroxyprolinebetaine, but contained appreciable levels of both glycinebetaine and trigonelline. Trigonelline was not detectable in the leaf tissue of any alfalfa genotype or cultivar evaluated.
A two-dimensional finite-difference numerical model is developed for the blood flow at the aortic bifurcation to determine the possible role of fluid dynamics in the atherogenesis. Arterial walls are assumed to be rigid, while the fluid is Newtonian. Parametric studies are performed to evaluate the effects of the area ratio, Reynolds number, corner curvatures, Womersley number, bifurcation angle and arterial pulsation on the flow and shear stresses. A high shear stress region exists on the inner wall distal to the vertex, while both high and low shear stress regions coexist along the outer wall. A temporary eddy is found along the outer wall, with more strength in the case of a higher area ratio. The results agree qualitatively with the existing experimental observations.