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Biomedical subjects

M Xiang

Publications and source records attributed to M Xiang.

At least 37 records · Page 2Linked to original sources
PubMed2000

[Osteopontin of skin and hair follicle of rat].

OBJECTIVE: To investigate the changes of osteopontin mRNA of skin and hair follicles of embryonic and postnatal rats. METHODS: The follicular cycles of rat hair were determined firstly and then the distribution and quantity of osteopontin mRNA on the paraffin sections of skin and hair follicles of Wistar rats were determined, aged from embryonic 14-18 days and postnatal 1-61 days, were investigated by radiolabel in situ hybridization technique. RESULTS: The results indicated that when the rats were 18 days old, the signals of osteopontin mRNA in dermal papilla (DP) of hair follicles were observed. The signals of osteopontin mRNA in DP showed a regular changes in the hair cycles: the signal of osteopontin mRNA appeared in the catagen phase and the peak level was in the middle stage of catagen, but it totally disappeared when the follicles entered into telegen and anagen phases of hair cycles. Osteopontin message was mainly accumulated in follicular dermal papillary cells, and in corresponding connective tissue sheath and neighboring dermal macrophages, but no signal of osteopontin mRNA was detected in any other skin and hair follicular cells else where. CONCLUSIONS: These results suggest a possible role of osteopontin in up-regulating growth and differentiation of dermal papilla during the catagen phase of the hair follicles.

Animals↗
PubMed1999

Prevention by rolipram of concanavalin A-induced T-cell-dependent hepatitis in mice.

Rolipram is a type IV phosphodiesterase inhibitor endowed with powerful immunomodulatory properties. In this study, we evaluated the effects of this drug on the development of the T-cell-mediated hepatitis inducible in mice by concanavalin A. The results indicated that prophylactic treatment with either 5 or 10 mg/kg rolipram injected intraperitoneally 24 h and 1 h prior to intravenous (i.v.) challenge with 20 mg/kg concanavalin A successfully ameliorated serological and histological signs of liver damage, so that the treated mice showed lower transaminase levels in the plasma and milder mononuclear cell infiltration of the liver as compared to vehicle-treated controls. Moreover, this effect was associated with profound modifications of circulating levels of cytokines released after concanavalin A injection, with the blood levels of interferon-gamma and tumor necrosis factor-alpha being significantly lower and those of interleukin-10 higher than those of the control mice. In particular, the increased blood levels of interleukin-10 might play an important role in the anti-hepatitic effects of rolipram as coadministering this compound with anti-interleukin-10 monoclonal antibody significantly reduced its anti-inflammatory action. These results suggest that rolipram may be useful in the clinical setting for the treatment of cell-mediated immunoinflammatory diseases such as immunoinflammatory hepatitis.

Animals↗
PubMed1999

Fluorophotometry in patients with human immunodeficiency virus with and without cytomegalovirus retinitis.

OBJECTIVE: To study the aqueous humor dynamics in subjects with human immunodeficiency virus (HIV) with and without cytomegalovirus (CMV) retinitis. DESIGN: Prospective cross-sectional study. PARTICIPANTS: Fourteen HIV-positive subjects (27 eyes, 19 with CMV retinitis and 8 without CMV retinitis), and a control group of 9 HIV-negative subjects (17 eyes). TESTING: Fluorophotometry. MAIN OUTCOME MEASURES: Aqueous flow rates as measured by fluorophotometry and intraocular pressure (IOP). RESULTS: Analysis of variance of the mean corrected aqueous flow rate revealed that both HIV-positive groups had significantly lower aqueous flow rates than did the control group (P < 0.03). No difference in mean aqueous flow rates was found between the HIV-positive eyes with or without CMV retinitis. Comparison of mean IOP revealed that HIV-positive eyes with CMV retinitis had significantly lower IOP than did the HIV-positive eyes without CMV retinitis (P = 0.03) and HIV-negative subjects (P = 0.002). There was no correlation between aqueous flow rate and IOP in HIV-positive subjects (P > 0.5). CONCLUSION: The lack of correlation between the aqueous flow rate and IOP suggests that there may be some disassociation between these parameters in HIV-positive patients. Further studies are needed to better understand the mechanism of aqueous formation and in the management of disorders affecting IOP in this population.

AIDS-Related Opportunistic Infections↗
PubMed1999

Composition of long chain polyunsaturated fatty acids in human milk and growth of young infants in rural areas of northern China.

The main source of fat in the diet in rural areas of northern China is soybean oil, therefore the pattern of essential fatty acids in human milk may be assumed to differ from that in milk from women in Western countries and to be similar to that of vegans. The concentrations of long chain polyunsaturated fatty acids in human milk and information on diet were analysed for 41 lactating women in rural areas of north China, and the growth of their infants was measured. The subjects were divided into two groups (group I, 1 mo postpartum; group II, 3 mo postpartum). The dietary intake of the mothers was high in carbohydrate and low in fat, protein and energy. The concentrations of linoleic acid (LA) and alpha-linolenic acid (LNA) were high. The ratio of LA to LNA, (21.6), was higher than has been reported from other countries. The concentration of docosa-hexaenoic acid (DHA) was low and the ratio of arachidonic acid (AA) to DHA was much higher (2.8) than recommended and similar to that found in vegans. The concentrations of AA and DHA in the milk correlated positively with the infants' weight gain at the third month (p<0.05) and of DHA with length gain at the first and third months (p<0.01). Since the concentration of AA and, particularly, DHA in the milk declined during lactation, DHA deficiency may appear after 3-4 mo of age in breastfed Chinese rural infants. Further studies of Chinese rural mother-infant pairs are necessary to prove whether supplementation with suitable sources of AA and DHA, such as fish oil, should be recommended as lactation is lengthened to ensure optimal infant growth and development.

Age Factors↗
PubMed1999

Relation between polyunsaturated fatty acids and growth.

Although it was discovered in the late 1920s that polyunsaturated fatty acids (PUFA) are essential for proper growth and development in animals, their nutritional importance in humans has not attained general interest until the 1990s, when the role for growth and development has been extensively studied in both humans and animals. It is now known that PUFA regulate various developmental and physiological processes, and that they are of essential importance for early human growth and development. Thus, linoleic acid is the precursor of arachidonic acid, from which hormone-like compounds, such as prostaglandins and leukotrienes, are formed, whereas alpha linolenic acid is the precursor of docosahexaenoic acid, which is an essential compound in cell membranes and occurs in particularly high concentration in the photoreceptors. In this paper the role of PUFA for human growth will be reviewed.

Animals↗
PubMed1999

Prophylaxis with the novel immunomodulator pidotimod reduces the frequency and severity of upper respiratory tract infections in children with Down's syndrome.

Down's syndrome (DS) is associated with several defects of both specific and non-specific immunity which may explain the enhanced susceptibility of DS subjects to viral and bacterial infections. In this study we have evaluated the effects of the new synthetic immunomodulator pidotimod in recurrent infections of the upper respiratory tract in a group of children with DS. It was an open trial vs untreated control, the pidotimod-treated group consisted of 14 subjects and the control group of 12. Pidotimod was administered at the dose of one 400 mg oral bottle/day for 90 days. There was a significant reduction in the frequency, severity and duration of infectious episodes in the pidotimod-treated group vs the untreated control group. The beneficial effects of pidotimod were also confirmed by a series of recordings made over the 90-day treatment period which showed a significant reduction in the number of days of fever, severity of the signs and symptoms of the acute episodes and use of antibiotics and antipyretic drugs. Pidotimod was well tolerated and no clinical, hematological or biochemical side-effects were noted.

Adolescent↗
PubMed1999

POU domain factor Brn-3a controls the differentiation and survival of trigeminal neurons by regulating Trk receptor expression.

Mice lacking the POU domain-containing transcription factor Brn-3a have several neuronal deficits. In the present paper, we show that Brn-3a plays two distinct roles during development of the trigeminal ganglion. In this ganglion, neurons expressing the neurotrophin receptors, TrkB and TrkC, are born between E9.5 and E11.5. In the absence of Brn-3a, very few neurons ever express TrkC, but TrkB-expressing neurons are present at E12.5 in elevated numbers, suggesting that Brn-3a may be a constituent of a regulatory circuit determining which Trk receptor is expressed by these early-born neurons. Most neurons expressing the neurotrophin receptor TrkA are generated between E11.5 and E13.5 in this ganglion and their initial generation is not prevented by absence of Brn-3a. However, after E12. 5, absence of Brn-3a results in a progressive loss in neuronal TrkA and TrkB expression, which leads to a massive wave of apoptosis that peaks at E15.5. Despite complete absence of the Trk receptors at E17. 5 and P0, approximately 30% of the normal complement of neurons survive to birth in Brn-3a mutants. Approximately 70% of these express the GDNF receptor subunit, c-ret; many can be sustained by GDNF, but not by NGF in culture. Thus, the vast majority of surviving neurons are probably sustained in vivo by trophic factor(s) whose receptors are not regulated by Brn-3a. In conclusion, our data indicate the specific functions of Brn-3a in controlling the survival and differentiation of trigeminal neurons by regulating expression of each of the three Trk receptors.

Animals↗
PubMed1999

Concanavalin A-induced hepatitis in mice is prevented by interleukin (IL)-10 and exacerbated by endogenous IL-10 deficiency.

One single intra-venous (i.v.) injection of Concanavalin A (Con A) into mice provokes a cell-mediated immunoinflammatory hepatitis. We have presently evaluated the immunopharmacological effects of exogenous interleukin (IL)-10 and the role of endogenous IL-10 in this model by using exogenous IL-10, anti-IL-10 monoclonal antibody (mAb) and mice with disrupted IL-10 gene (IL-10 KO mice). Whilst exogenous IL-10 administered in a prophylactic (1 h prior to Con A) and even "early" therapeutic fashion (30 min after Con A) reduced the elevation of transaminase activities in plasma in a dose-dependent manner, observed in control mice, these biochemical markers of liver injury were significantly increased both in IL-10 KO mice as well as in those receiving anti-IL-10 mAb. Interestingly, doses of Con A lower than 20 mg/kg that were only capable of inducing slight serological signs of hepatitis in mice, exerted marked hepatitic effects when administered to either anti-IL-10 mAb-treated mice or to IL-10 KO mice. The disease modulating effects of exogenous IL-10 and either genetical or pharmacologically-induced IL-10 deficiency were associated with profound and opposite modifications of the Con A-induced increase in the circulating levels of IFN-gamma and TNF-alpha. Relative to control animals, the blood levels of these cytokines were diminished in IL-10-treated mice and augmented in both IL-10 KO mice and anti-IL-10 mAb-treated mice. These results prove the physiological antiinflammatory role of endogenous IL-10 in Con A induced hepatitis and the beneficial effects of IL-10 treatment to prevent this condition.

Alanine Transaminase↗
PubMed1999

Failure of exogenously administered interferon-gamma or blockage of endogenous interleukin-4 with specific inhibitors to augment the incidence of autoimmune diabetes in male NOD mice.

Interferon (IFN)-gamma and interleukin (IL)-4 are prototypic type 1 and type 2 cytokines which are known to play pathogenetic and protective roles, respectively, in NOD mouse IDDM. The capacity of male NOD mice to produce more IL-4 and less IFN-gamma within the insulitic lesions than females has been suggested to contribute to their lower incidence of diabetes. In this study we have tested the effects of prolonged prophylactic treatment of male NOD mice with rat IFN-gamma, mouse IFN-gamma, anti-IL-4 monoclonal antibody (mAb) and recombinant murine soluble IL-4 receptor (smIL-4R) on the diabetogenic events leading to insulitis and diabetes. None of these treatments influenced spontaneous and/or cyclophosphamide-induced autoimmune diabetogenesis in male NOD mice. Control mice exhibited comparable histological signs of insulitis and incidence of diabetes to those treated with either mouse/rat IFN-gamma or specific IL-4 inhibitors. On the contrary, both clinical and histological signs of diabetes were suppressed by prophylactic treatment with anti-IFN-gamma mAb. These findings indicate that the autoimmune diathesis of male NOD mice towards IDDM cannot be augmented by manipulation of endogenous IFN-gamma or IL-4.

Animals↗
PubMed1999

Reproductive and hormonal risk factors for thyroid cancer in Los Angeles County females.

We conducted an individually matched case-control study (292 pairs) of female thyroid cancer patients to examine the role of reproductive history and exogenous hormones in this disease. Radiation treatment to the head or neck [28 cases and 2 controls exposed; odds ratio (OR), 14.0; 95% confidence interval (CI), 3.5-121.3] and certain benign thyroid diseases (including adolescent thyroid enlargement, goiter, and nodules or tumors) were strongly associated with thyroid cancer. Irregular menstruation increased risk (OR, 1.8; 95% CI, 0.9-3.7). Age at menarche and pregnancy history were not related to disease. Women with natural menopause and hysterectomized women without oophorectomy had no increase in risk, but disease risk was elevated in women with bilateral oophorectomy (OR, 6.5; 95% CI, 1.1-38.1). In general, use of oral contraceptives and other exogenous estrogens was not associated with thyroid cancer. However, risk increased with number of pregnancies in women using lactation suppressants (P = 0.03) and decreased with duration of breastfeeding (P = 0.04). These data provide only limited support for the hypothesis that reproductive and hormonal exposures are responsible for the marked excess of thyroid cancer risk in adult females.

Adenocarcinoma, Follicular↗
PubMed1998

Requirement for Brn-3b in early differentiation of postmitotic retinal ganglion cell precursors.

The Brn-3 subfamily of POU domain transcription factors consists of Brn-3a, -3b, and -3c, which are important regulators for sensorineural development. Despite the expression of all three factors in retinal ganglion cells, earlier studies have shown that Brn-3b is the only one among the three Brn-3 genes that is essential for development of approximately 70% of ganglion cells in the murine retina. I report here that Brn-3b displays a spatiotemporal expression pattern characteristic of the dynamic profile of ganglion cell genesis during murine retinal development. Moreover, it is initially turned on in postmitotic ganglion cell precursors 2 days before the onset of Brn-3a and -3c expression in differentiated ganglion cells. During the entire period of retinal ganglion cell genesis, the postmitotic ganglion cell precursors that would normally become Brn-3b+ cells fail to properly differentiate in Brn-3b-/- mice, as evidenced by a twofold reduction in the optic nerve size and diminished expression of several ganglion cell markers. The undifferentiated ganglion cell precursors appear to be degenerated by apoptosis within the ganglion cell layer during the perinatal and early postnatal period. I propose that retinal ganglion cells develop following two separate differentiation pathways--Brn-3b dependent and Brn-3b independent. In the Brn-3b-dependent mechanism, Brn-3b may be required to initiate a particular differentiation program for a large set of postmitotic ganglion precursors to properly differentiate into the 70%, Brn-3b-dependent retinal ganglion cells.

Animals↗
PubMed1998

Requirement for Brn-3c in maturation and survival, but not in fate determination of inner ear hair cells.

Mutations in the POU domain gene Brn-3c causes hearing impairment in both the human and mouse as a result of inner ear hair cell loss. We show here that during murine embryogenesis, Brn-3c is expressed in postmitotic cells committed to hair cell phenotype but not in mitotic progenitors in the inner ear sensory epithelium. In developing auditory and vestibular sensory epithelia of Brn-3c-/- mice, hair cells are found to be generated and undergo initial differentiation as indicated by their morphology, laminar position and expression of hair cell markers, including myosins VI and VIIa, calretinin and parvalbumin. However, a small number of hair cells are anomalously retained in the supporting cell layer in the vestibular sensory epithelia. Furthermore, the initially differentiated hair cells fail to form stereociliary bundles and degenerate by apoptosis in the Brn-3c-/- mice. These data indicate a crucial role for Brn-3c in maturation, survival and migration of hair cells, but not in proliferation or commitment of hair cell progenitors.

Animals↗
PubMed1998

[A longitudinal study on deterioration of physical function in people aged over 55 in Beijing].

The objective of this study is to explore the index of physical performance test in detecting physical functional status among elderly people. Physical performance test, recommended by Yale University in EPESE was used in the study. A total number of 1,986 people aged 55 and over in urban and rural area of Beijing was studied in a three-year longitutinal observation. Among 1,986 cases studied in 1992, 168 died between 1992-1994. The mortality rate increased along with the degree of functional disablement, lowest in non-disabled (3.4%), followed by mild ones (5.2%), moderate (10.5%) and highest in severely disabled (18.4%). It is shown that performance test can be used as a tool in observing and detecting risk groups in the progress of functional disability It's an important index describing the decline of health status.

Aged↗
PubMed1998

[Will chronic nonproductive cough with bronchial hyperresponsiveness be cough variant asthma?].

OBJECTIVE: The clinical characteristics of the patients suffered from chronic nonproductive cough with bronchial hyperresponsiveness were analyzed, so as to evaluate the value of measurement of bronchial responsiveness in diagnosis of cough variant asthma (CVA). METHOD: 124 patients with chronic nonproductive cough were divided into two groups after the measurement of bronchial responsiveness: cough bronchial hyperresponsiveness positive group (CBH-P, n = 35) and cough bronchial hyperresponsiveness negative group (CBH-N, n = 33). Routine pulmonary function, positive rate of antigen-skin pitting lest, count of blood eosinophil cells, level of blood IgE, positive rate of prednisone test and the number of development of classical asthma in two-year following up were studied. RESULT: The percentage of FEV1.0 in group CBH-P was significantly lower than in group CBH-N, but antigen-skin pitting test, count of blood eosinophil cells, prednisone test and the number of development of classic asthma in two-year following up were all higher than in the latter group. In group CBH-P, there was no significant difference in positive rate of antigen-skin pitting test, routine pulmonary function, reacting threshold(Dmin) and wheezing threshold (DCW/Dmin) between the patients who developed classic asthma and those who did not. CONCLUSION: The measurement of bronchial responsiveness is important for the diagnosis of CVA, but it is not the only diagnostic criteria and should be combined with other clinical data.

Adult↗
PubMed1998

[A study of Nexin 1 of skin and hair follicle during postnatal development period of rat].

OBJECTIVE: The changes of Nexin 1 mRNA of skin hair follicles of postnatal rats were investigated on tissue sections in this paper in order to get more information about the possible functions of Nexin 1 in regulating of hair growth and cycle. METHODS: The distribution and quantity of Nexin 1 mRNA on the paraffin sections of skin and hair follicle of Wistar rats, aged from postnatal 1 day to 61 day, were investigated by radiolabel In Situ Hybridization technique. RESULTS: When the rats were 4 days old, the signals of Nexin 1 mRNA in the follicular papillary cells were observed. The signals of Nexin 1 mRNA showed a regular changes in the hair cycles: the signal of Nexin 1 mRNA appeared in the early stage of anagen phase and became higher level gradually, the peak was in the middle-late(IV) stage of anagen and decreased in later anagen but it totally disappeared when the follicles entered into catagen and telegen phases of hair cycles. Nexin 1 message was only accumulated in follicular papillary cells but no signal of Nexin 1 mRNA was detected in any other skin and hair follicular cells, including dermal fibroblasts, mast cells, adipocytes, endothelial or muscle cells, keratinocytes of skin and in different layers of hair follicle were showing also negative. CONCLUSIONS: These results suggested a possible role of Nexin 1 which was a potent serine-protease inhibitor and have been shown in many organs to play important roles in regulating cellular growth and differentiation in regulating hair follicular growth.

Amyloid beta-Protein Precursor↗
PubMed1998

[Determination of total Ca in the lung tissue of rats by FAAS].

Determination of total Ca in the Lung Tissue of Rats by FAAS was described, with a mixed microemulsion consisting of sodium dodecyl sulfate, N-dodecyl, N-dimethyl benzol ammonium bromide and nonyl phenol polyethyeneoxy ether. Comparing the result of the microemulsion FAAS with that of solution FAAS showed that the former was better than the latter in sensitivity, precision, selectivity and linearity of the calibration curve, with a detection limit of 1.92 microg x cm(-3), relative standard deviation of 1.92% (n = 10) and linear regressive coefficient of 0.9998 of the calibration curve over 0-20 microg x cm(-3) calcium. The method was applied to determine calcium amount in the lung tissue of rats, and the results were in accordance with those odtained by the conventional solution FAAS, in which a sample was reduced to ashes at a high temperature.

Analytic Sample Preparation Methods↗
PubMed1997

Essential role of POU-domain factor Brn-3c in auditory and vestibular hair cell development.

The Brn-3 subfamily of POU-domain transcription factor genes consists of three highly homologous members-Brn-3a, Brn-3b, and Brn-3c-that are expressed in sensory neurons and in a small number of brainstem nuclei. This paper describes the role of Brn-3c in auditory and vestibular system development. In the inner ear, the Brn-3c protein is found only in auditory and vestibular hair cells, and the Brn-3a and Brn-3b proteins are found only in subsets of spiral and vestibular ganglion neurons. Mice carrying a targeted deletion of the Brn-3c gene are deaf and have impaired balance. These defects reflect a complete loss of auditory and vestibular hair cells during the late embryonic and early postnatal period and a secondary loss of spiral and vestibular ganglion neurons. Together with earlier work demonstrating a loss of trigeminal ganglion neurons and retinal ganglion cells in mice carrying targeted disruptions in the Brn-3a and Brn-3b genes, respectively, the Brn-3c phenotype reported here demonstrates that each of the Brn-3 genes plays distinctive roles in the somatosensory, visual, and auditory/vestibular systems.

Animals↗