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Biomedical subjects

J Hao

Publications and source records attributed to J Hao.

At least 19 recordsLinked to original sources
PubMed1998

Visualization of penicillin-binding proteins during sporulation of Streptomyces griseus.

We used fluorescein-tagged beta-lactam antibiotics to visualize penicillin-binding proteins (PBPs) in sporulating cultures of Streptomyces griseus. Six PBPs were identified in membranes prepared from growing and sporulating cultures. The binding activity of an 85-kDa PBP increased fourfold by 10 to 12 h of sporulation, at which time the sporulation septa were formed. Cefoxitin inhibited the interaction of the fluorescein-tagged antibiotics with the 85-kDa PBP and also prevented septum formation during sporulation but not during vegetative growth. The 85-kDa PBP, which was the predominant PBP in membranes of cells that were undergoing septation, preferentially bound fluorescein-6-aminopenicillanic acid (Flu-APA). Fluorescence microscopy showed that the sporulation septa were specifically labeled by Flu-APA; this interaction was blocked by prior exposure of the cells to cefoxitin at a concentration that interfered with septation. We hypothesize that the 85-kDa PBP is involved in septum formation during sporulation of S. griseus.

Anti-Bacterial Agents↗
PubMed1997

Determination of Association Constants for Cyclodextrin-Surfactant Inclusion Complexes: A Numerical Method Based on Surface Tension Measurements

Inclusion complexes of beta-cyclodextrin (beta-CD) with sodium octyl sulfonate (C8As), sodium dodecyl sulfonate (C12As), and sodium hexadecyl sulfonate (C16As) in aqueous solutions are studied by surface tension measurement at the air/water interface at different temperatures. At fixed concentrations of the surfactants, the surface tension increases with an increase in beta-CD concentration to a maximum value, at which it holds. The surface tension curves of the surfactants in the presence of beta-CD are higher than those in the absence of beta-CD. The curves rise higher with the increase in beta-CD concentration for each surfactant. The apparent critical micelle concentrations (CMC*) of the surfactants vary linearly with beta-CD concentration. The CMC* and surface tension values (including those after the CMC*) for the same system decrease with increase in temperature. A numerical method based on surface tension measurements is developed to determine the association constants for 1:1 inclusion complexes. This method is very reliable and easy to perform. The results demonstrate that the longer the hydrophobic tail of the surfactant, the greater the association constant with beta-CD, and that for the same surfactant the association constant is higher at lower temperatures.

Journal Article↗
PubMed1997

Mineralized nodule formation by human dental papilla cells in culture.

Human dental papilla cells were enzymatically separated from deciduous tooth germs of an 8-month-old embryo legally aborted. The second passage cells were cultured up to 35 days in 3 groups. The beta-GP group was cultured in the Dulbecco MEM containing ascorbic acid and beta-glycerophosphate supplemented with 15% fetal bovine serum. The Dex group was in the same medium, in addition containing dexamethasone. The control group contained none of the 3 chemicals. Mineralized nodules were formed after 15 days in the beta-GP and Dex groups. Only in the presence of ascorbic acid and organic phosphate did they mineralize. The addition of dexamethasone caused a significant increase in the number of nodules. By electron microscopy, the nodules contained needle-shaped crystals associated with a network of collagen fibrils. Calcium and phosphorus were detected by energy-dispersive X-ray microanalysis in the nodules. Furthermore, the crystalline material exhibited a pattern consistent with hydroxyapatite and dentin when examined by X-ray diffractometry. Cells showed high levels of alkaline phosphatase activity, which was increased 2-3 times in the presence of the 3 chemicals. These results indicated that human dental papilla cells have the ability to form dentin in culture. The formation of mineralized nodules by human dental papilla in vitro provides a useful model for studying the morphogenesis and differentiation of dental papilla ectomesenchyme.

Alkaline Phosphatase↗
PubMed1997

Differential expression of cytokeratin mRNA and protein in normal prostate, prostatic intraepithelial neoplasia, and invasive carcinoma.

The expression of cytokeratin (CK) mRNA for CK5, -8, -14, -16, and -19 was investigated in normal prostate, prostatic intraepithelial neoplasia (PIN) lesions, and invasive carcinoma using in situ hybridization. Protein localization was carried out in adjacent sections using immunohistochemistry and correlated with mRNA expression. Snap-frozen human prostate samples including 22 examples of normal glands, 20 cases of PIN lesions, and 12 cases of invasive carcinoma were examined. CK5 and -14 mRNA and protein were prominently expressed only in the basal cells of normal glands and PIN lesions. CK14 mRNA was absent in the luminal cells of the most of the PIN lesions but was seen at a low level in some PIN lesions. CK14 protein was not detected in any PIN lesion, suggesting that, if the cell that makes up the PIN lesions is derived from a basal cell, CK14 translation is depressed although a low level of CK14 mRNA may persist. CK8 mRNA and protein were constitutively expressed in all epithelia of normal and abnormal prostate tissues. CK19 mRNA and protein were persistently expressed in both basal and luminal cells of the tubular portion of normal glands as well as PIN lesions, but were expressed heterogeneously in both basal and luminal cells of normal alveoli. CK16 mRNA was expressed in a similar pattern as CK19, but CK16 protein was not detected either in normal or in abnormal prostate tissues. In conclusion, the expression of CK19 in PIN lesions is similar to its tubular expression and would support an origin of PIN lesions from this structure rather than the alveolar portion of the glands. The similar cytokeratin expression between PIN lesions and invasive carcinoma further supports the concept that PIN is a precursor lesion of invasive carcinoma.

Carcinoma↗
PubMed1996

Differential expression of laminin 5 (alpha 3 beta 3 gamma 2) by human malignant and normal prostate.

Laminin 5 is an extracellular matrix protein integral to the formation of the hemidesmosomes that attach normal basal cells to the underlying basal lamina. We have shown that these hemidesmosomal complexes are lost in prostate carcinoma, possibly allowing malignant cells to detach from the anchoring structures and then to invade and migrate through the adjacent tissue. Our previous immunohistochemical studies of normal and malignant human prostate tissue demonstrated that the laminin subchains alpha 1, alpha 2, beta 1, beta 2, gamma 1, and gamma 2 were all expressed as normal components of the basal lamina surrounding prostate glands. Although most of these subchains were also expressed by the de novo basal lamina synthesized by prostate carcinoma, the gamma 2 subchain of laminin 5 was not detected. In an effort to investigate the role laminin 5 plays in the tumorigenesis of prostate carcinoma, the protein expression of the three subchains of laminin 5 (alpha 3, beta 3, and gamma 2) was compared in normal prostate, prostatic intraepithelial neoplasia, and invasive carcinoma using immunohistochemistry. The results showed that the protein for the alpha 3 subchain of laminin 5 is retained by both normal prostate epithelium and prostate carcinoma, but the beta 3 and the gamma 2 subchains were not detected in invasive carcinoma. Despite the absence of the gamma 2 protein, however, the carcinoma cells continued to express substantial amounts of the gamma 2 mRNA. Although it is unclear how the gene for the gamma 2 subchain of laminin 5 is regulated, results of this study suggest that there is a post-transcriptional defect in the expression of the gamma 2 subchain that occurs during the progression from a premalignant lesion to invasive carcinoma. As laminin 5 is a component of the anchoring filaments, the failure to express the gamma 2 subchain may contribute to the failure to form anchoring filaments and hemidesmosomes. This failure of hemidesmosome formation results in a less stable epithelial-stromal junction, which may allow malignant cells more potential to invade and spread through adjacent structures.

Blotting, Northern↗
PubMed1996

Differences in pituitary expression of proopiomelanocortin in Dahl salt-resistant and salt-sensitive rats on a high salt diet.

The Dahl strain of genetically salt resistant (R) and salt sensitive (S) rats affords an opportunity to explore mechanisms for salt resistance and sensitivity. Because of the evidence that opioid peptides and their receptors can be involved in cardiovascular regulation, the objective of this study was to test the hypothesis that proopiomelanocortin (POMC), the precursor of beta-endorphin, is involved in the development of hypertension, through the determination of POMC mRNA in the pituitary. Three-week-old inbred Dahl R and S rats were maintained on a high salt diet (8% NaCl) or low salt diet (0.4% NaCl) for 6 weeks. POMC mRNA and for comparison preproenkephalin A (preproENK) mRNA were examined from tissues of Dahl R and S rats as determined by Northern blot analysis using beta-actin as an internal standard. POMC mRNA was abundant in the pituitary tissues. There was more POMC mRNA in the pituitary tissue of R rats compared with that of S rats on the high salt diet. Differences in POMC mRNA in the pituitary were not observed between R and S on the low salt diet. There were no differences in the levels of preproENK mRNA in the pituitary tissues of R and S rats on high or low salt diet. From these data, we propose that inefficient production of POMC mRNA is a characteristic of the Dahl S rat on a high salt diet.

Animals↗
PubMed1995

Prevalence of hypertension and its trends in Chinese populations.

The third nation-wide survey of blood pressure level and hypertension was carried out in China in 1991. In total, 950,356 residents aged > or = 15 years were examined. Sampling population were composed of half urban and half rural from 27 provinces or autonomous regions and three municipalities. The results showed that: (1) the age-adjusted prevalence rate of hypertension (systolic blood pressure > or = 140 mmHg or diastolic blood pressure > or = 90 mmHg) was 11.26% (male 12.15%, female 10.32%) and the definite hypertension rate (systolic blood pressure > or = 160 mmHg or diastolic blood pressure > or = 95 mmHg, or on medication) was 5.29% (male 5.38%, female 5.21%); rate of borderline hypertension was evaluated from 2.82% to 6.15% during the 10-year period from 1979/1980 to 1991; (2) the prevalence rate was progressively increased with age, especially after age 35; prevalence rates were generally higher in men than women before about age 44, however by age 60, women had a higher prevalence of hypertension; (3) a general trend of decrease in prevalence from north-eastern to south-western China was confirmed; (4) there were significantly lower rates in rural than in urban areas. Results of preliminary analysis for prevalence of hypertension among different occupations, nationalities, and educational levels were presented.

Adolescent↗
PubMed1995

Hypertension prevalence and status of awareness, treatment and control in China.

A nation-wide survey of blood pressure (BP) and high BP was made in China in 1991, using standardized methods and covering 950,356 men and women aged 15 years and above, from 30 provinces, autonomous regions, and municipalities. The purpose of the study was to estimate the prevalence and the status of awareness, treatment, and control of hypertension. The overall prevalence rate of hypertension defined as systolic BP > or = 140 or diastolic BP > or = 90 mmHg or currently on antihypertensive medication was 13.6%, and was higher in urban (16.3%) than in rural (11.1%) setting. The rate was 6.6% if a BP cut-point of 160/95 mmHg was used. Rates were low in younger age-groups but rose sharply after age 45. The total number of hypertensives in 1990 was estimated to be close to 90 millions. Of all hypertensives, about 1/4 were aware of their high BP, half of these were on medication, and only 3% had their BP controlled. All the rates were higher if the BP cut-point was 160/95 mmHg. Higher rates were found in urban than rural setting and, to a lesser degree, for women than men. In conclusion, hypertension was found to be common in China, and the rates of awareness, drug treatment, and controlled BP were low, indicating an urgent need for developing a national program of treatment and prevention of high BP.

Adolescent↗
PubMed1995

Electric acupuncture treatment of peripheral nerve injury.

54 cases of peripheral nerve injury were treated by electric acupuncture and compared with 54 control cases treated with supportive medication. The changes after treatment were observed chiefly by electromyography while sensory and motor improvement were also recorded as auxiliary indicators. The therapeutic results in the acupuncture group were 5 cases cured, 26 markedly effective, 19 improved, and 4 cases failed, a total effective rate of 92.6% in contrast to the 55.6% for the controls. Analysis of the therapeutic results showed that 1) those in the acupuncture group were significantly better than in the control group; 2) nerve injuries should be treated as early as possible; 3) the radial nerve and the common peroneal nerve recovered faster than others; 4) cases not surgically explored recovered faster than those that were, and 5) patients with prompt propagation of the needling sensation recovered significantly faster than those with slow propagation.

Acupuncture Therapy↗
PubMed1995

Expression of hemidesmosomal and extracellular matrix proteins by normal and malignant human prostate tissue.

The progression of prostate carcinoma may be influenced by the biochemical nature of the basal lamina surrounding the primary carcinoma cells. As a first step toward understanding this process, the composition and structure of the basal lamina in normal prostate, prostatic intraepithelial neoplasia, and human carcinoma were determined. In addition, a comparison was made between the attachments of the normal basal cell to its underlying basal lamina and those made by primary prostate carcinoma. The normal basal cells form both focal adhesions and hemidesmosomal-like structures as observed by transmission electron microscopy. The normal basal cells exhibited a polarized distribution of hemidesmosomal associated proteins including BP180, BP230, HD1, plectin, laminin-gamma 2(B2t), collagen VII, and the corresponding integrin laminin receptors alpha 6 beta 1 and alpha 6 beta 4. The expression and distribution pattern of these proteins were retained in the prostate intraepithelial neoplasia lesions. In contrast, the carcinoma cells uniformly lacked hemidesmosomal structures, the integrin alpha 6 beta 4, BP180, laminin-gamma 2 (B2t), and collagen VII but did express BP230 (30%), plectin, HD1 (15%), and the integrin laminin receptors alpha 3 beta 1 and alpha 6 beta 1. These results suggest that, although a detectable basal lamina structure is present in carcinoma, its composition and cellular attachments are abnormal. The loss of critical cellular attachments may play a role in influencing the progression potential of prostate carcinoma.

Carcinoma↗
PubMed1994

A new model of neural associative memories.

In this paper, we present a new model of discrete neural associative memories and its design rule. The most important feature of this new model is that a static mapping instead of the dynamic convergent process is used to retrieve the stored messages. The new model features a two-layer structure, with feedforward connections only and uses two kinds of neurons which implement different output functions. Another important feature is that this new model employs an extremely simple weight setup rule and all the resulted weights can only assume two different values, -1 and +1, which facilitates the VLSI implementation. Compared to the famous discrete Hopfield model designed with the well-known Hebbian rule or any other rule, the new model can guarantee all the given patterns to be stored as fixed points. Moreover, each fixed point is surrounded by an attraction basin (which is a ball in the Hamming distance sense) with the maximal possible radius. The performances of the new model are compared through some illustrative examples with those of the Hopfield associative memory designed using different methods.

Association↗
PubMed1994

Predictive control of nonlinear systems based on identification by backpropagation networks.

Using the property of universal approximation of multilayer perceptron neural network, a class of discrete nonlinear dynamical systems are modeled by a perceptron with two hidden layers. A backpropagation algorithm is then used to train the model to identify the nonlinear systems to a desired level of accuracy. Based on the identified model, a one-step-ahead predictive control scheme is proposed in which the future control inputs are obtained through some nonlinear optimization process. Making use of the online learning properties of neural networks, the predictive control scheme is further developed into an adaptive one which is robust to the incompleteness of identification. Simulation results show that this neural control scheme works well even for some very complicated nonlinear systems.

Mathematics↗
PubMed1993

A rule-based neural controller for inverted pendulum system.

This paper tries to demonstrate how a heuristic neural control approach can be used to solve a complex nonlinear control problem. The control task is to swing up a pendulum mounted on a cart from its stable position (vertically down) to the zero state (up right) and keep it there by applying a sequence of two opposing constant forces of equal magnitude to the mass center of the cart. In addition, the displacement of the cart itself is confined to within a preset limit during the swinging up action and it will eventually be brought to the origin of the track. This is truly a nontrivial nonlinear regulation problem and is considerably difficult compared to the pendulum balancing problem (and its variations) widely adopted as a benchmarking test system for neural controllers. Through the solution of this specific control problem, we try to illustrate a heuristic neural control approach with task decomposition, control rule extraction and neural net rule implementation as its basic elements. Specializing to the pendulum problem, the global control task is decomposed into subtasks namely pendulum positioning and cart positioning. Accordingly, three separate neural subcontrollers are designed to cater to the subtasks and their coordination, i.e., pendulum subcontroller (PSC), cart subcontroller (CSC) and the switching subcontroller (SSC). Each of the subcontrollers is designed based on the rules and guidelines obtained from the experiences of a human operator. The simulation result is included to show the actual performance of the controller.

Algorithms↗
PubMed1991

The role of oxygen free radicals in myocardial ischemia/reperfusion injury.

A series of experiments have been done to investigate the role of oxygen free radicals in ischemia/reperfusion injury. The following results were found: Myocardial MDA content increased significantly after post-ischemic reperfusion in vivo and in vitro. A blockade of the xanthine oxidase pathway for free radical generation could provide effective protection against ischemia/reperfusion injury. Exogenous reactive oxygen intermediates H2O2, .OH and O2- could induce changes in the contractility and electrophysiological properties of myocardial cells similar to those seen in ischemia/reperfusion. An outburst of free radical generation was detected by ESR spectroscopy at low temperature (-173 degrees C) and with the spin trapping technique during the very early phase of reperfusion. The authors emphasize the important role of free radicals in the pathogenesis of myocardial ischemia/reperfusion injury.

Action Potentials↗
PubMed1990

Local corticosteroid application blocks transmission in normal nociceptive C-fibres.

The effect of a locally applied depot form of a corticosteroid on the electrical properties of nerves was investigated in an experimental model. The segmental transmission in electrically stimulated A-fibres and in C-fibres of the plantar nerve in the anaesthetized rat was utilized. A drop of methylprednisolone acetate or vehicle constituent was placed on the dissected plantar nerve proximal to the stimulating electrodes after recording control responses (A-fibre volley in the sciatic nerve and C-fibre evoked reflex discharge in flexor motoneurons). The corticosteroid was found to suppress the transmission in thin unmyelinated C-fibres but not in myelinated A-beta fibres. The effect was found to be due to the corticosteroid per se. The effect was reversed when the corticosteroid was removed, which suggests a direct membrane action.

Administration, Topical↗
PubMed1990

[Studies on the low skin impedance points and the feature of its distribution along the channels by microcomputer. I. Observation on the reliability of the measurement].

According to the requirement of channel research, a system for the measurement of skin impedance had been designed and a series of experiments to check the reliability of this system had also been done. The facts demonstrated that the pressure exerted by the exploring electrode, the duration of switch-on as well as the number of times of repeated measurements all showed no conspicuous influences on the skin impedance. The results are stable and reliable. Moreover, the measurement and data processing are controlled by microcomputer. Thus, the method of measurement of skin impedance along the channels has been developed to a higher level. Under the conditions of our experiment, the impedance of the low skin impedance points (LSIPs) are about 108k omega, which are quite low than that of the non-LSIPs around them. The difference between the two is highly significant. Both the impedance of LSIPs and non-LSIPs are stable, without marked variation. These results provide the prerequisites indispensable for the further observation on the feature of the distribution of LSIPs.

Acupuncture Points↗
PubMed1989

Regulation of extracellular proteins and alpha-amylase secretion by temperature in Bacillus subtilis.

alpha-Amylase was found to be the main protein secreted by Bacillus subtilis, corresponding to 90, 87 and 60% of total extracellular proteins at 30, 40 and 45 degrees C, respectively. A change in temperature can affect the pattern of proteins secreted as detected by gel electrophoresis. 14C-Leucine incorporation into extracellular proteins and their proportion at the end of the growth phase was higher at 30 degrees C than that at 40 or 45 degrees C. The effect of temperature on alpha-amylase synthesis as determined by its enzymic activity and on the extracellular protein synthesis followed a similar pattern.

Bacillus subtilis↗