Search PubMed⌕ Search

Biomedical subjects

A Li

Publications and source records attributed to A Li.

At least 145 records · Page 8Linked to original sources
PubMed1999

rRNA gene internal transcribed spacer 1 and 2 sequences of asexual, anthropophilic dermatophytes related to Trichophyton rubrum.

The ribosomal region spanning the two internal transcribed spacer (ITS) regions and the 5.8S ribosomal DNA region was sequenced for asexual, anthropophilic dermatophyte species with morphological similarity to Trichophyton rubrum, as well as for members of the three previously delineated, related major clades in the T. mentagrophytes complex. Representative isolates of T. raubitschekii, T. fischeri, and T. kanei were found to have ITS sequences identical to that of T. rubrum. The ITS sequences of T. soudanense and T. megninii differed from that of T. rubrum by only a small number of base pairs. Their continued status as species, however, appears to meet criteria outlined in the population genetics-based cohesion species concept of A. R. Templeton. The ITS sequence of T. tonsurans differed from that of the biologically distinct T. equinum by only 1 bp, while the ITS sequence of the recently described species T. krajdenii had a sequence identical to that of T. mentagrophytes isolates related to the teleomorph Arthroderma vanbreuseghemii.

Arthrodermataceae↗
PubMed1999

TRH microdialysis into the RTN of the conscious rat increases breathing, metabolism, and temperature.

Thyrotropin-releasing hormone (TRH) injected into the retrotrapezoid nucleus (RTN) of anesthetized rats produces a large, prolonged stimulation of ventilatory output (C. L. Cream, A. Li, and E. E. Nattie. J. Appl. Physiol. 83: 792-799, 1997). Here we inject or dialyze TRH into the RTN of conscious rats. In 6 of 17 injections (200 nl, 3.1 +/- 1.7 mM), ventilation (VE) increased 31% by 10 min, with recovery by 60 min. With dialysis, each animal of one group (n = 5) received, in random order, 10 mM TRH, 10 mM TRHOH (a metabolite of TRH), and artificial cerebrospinal fluid (aCSF); each animal of a second group (n = 5) received aCSF and 1 mM TRH. TRHOH and aCSF had no sustained effects. TRH (1 mM) increased VE (32%, P < 0.02, by 10 min, with recovery by 60 min), O(2) consumption (VO(2); 19%, P < 0. 03), and body (rectal) temperature (T(re); 0.5 degrees C, P < 0.09). TRH (10 mM) increased VE (78%, P < 0.01, by 10 min, with no recovery at 60 min), VO(2) (48%, P < 0.01), and T(re) (1.0 degrees C, P < 0. 01). TRH also induced arousal. The tissue volume affected in dialysis, estimated by spread of dialyzed fluorescein (332.3 mol wt, mol wt of TRH = 362.4), was 1,580 +/- 256 nl for 10 mM (n = 5) and 590 +/- 128 nl for 1 mM (n = 5). We conclude that 1) the RTN is involved in the integration of VE, VO(2), T(re), and arousal and 2) TRH may establish the responsiveness of RTN neurons.

Animals↗
PubMed1999

CO(2) microdialysis in retrotrapezoid nucleus of the rat increases breathing in wakefulness but not in sleep.

Central chemoreceptors are widespread within the brain stem. We suggest that their function at some sites may vary with the state of arousal. In this study, we tested the hypothesis that the function of chemoreceptors in the retrotrapezoid nucleus (RTN) varies with sleep and wakefulness. In unanesthetized rats, we produced focal acidification of the RTN by means of a microdialysis probe (tip containing the semipermeable membrane = 1-mm length, 240-microm diameter, and 45-nl volume). With the use of a dialysate equilibrated with 25% CO(2), the tissue pH change (measured in anesthetized animals) was 1) limited to within 550 microm of the probe and, 2) at the probe tip, was equivalent to that observed with end-tidal PCO(2) of 63 Torr. This focal acidification of the RTN increased ventilation significantly by 24% above baseline, on average, in 13 trials in seven rats only during wakefulness. The effect was entirely due to an increase in tidal volume. During sleep defined by behavioral criteria, ventilation was unaffected, on average, in 10 trials in seven rats. During sleep, the chemoreceptors in the RTN appear to be inactive, or, if active, the respiratory control system either is not responding or is responding with very low gain. Because ventilation is increased during sleep with all central chemoreceptor sites stimulated via systemic CO(2) application, other central chemoreceptor locations must have enhanced effectiveness.

Acidosis↗
PubMed1999

Efficiency of leukocyte removal by filters made of superfine glass fiber membranes.

BACKGROUND AND OBJECTIVES: To demonstrate the application of leukocyte removal filters made of a new type of filter material - superfine glass fiber - for depleting leukocytes in SAGM red cell suspensions and preventing nonhemolytic transfusion reactions. MATERIALS AND METHODS: The extent of leukocyte depletion and red cell recovery was based on cell counts. Trace leukocytes were counted in a 50-microl Nageotte counting chamber or by using a flow cytometer. The chemical stability of the glass fiber membranes was studied by plasma emission spectrometer and by measuring the ion content and weighing nonvolatile matter in water extract. The structural stability of the glass fiber membranes was studied by a micropore-filter membrane method. RESULTS: Leukocyte removal filters made of superfine glass fiber membranes removed more than 99.0% of leukocytes in SAGM red cell suspensions prepared from 400 ml whole blood. Red cell recovery exceeded 90%, and the total number of residual leukocytes was less than 5x10(6). A water extract of the glass fiber membranes contained only traces of Si4+ and Ca2+ and less than 2 mg/100 ml of nonvolatile matter. No broken or loose fibers were found in the filters. Scanning electron microscopy showed that the web structure of the glass fiber membranes was instrumental in trapping and holding leukocytes. CONCLUSION: A filter made of glass fiber membranes is effective in leukocyte depletion.

Adenine↗
PubMed1999

Leptin gene expression in the brain and pituitary gland.

The adipocyte-derived hormone, leptin, and its receptor, are now known to be integral components of a physiological signalling system that regulates fuel stores and energy balance. Constitutive leptin expression has been demonstrated only in adipose tissue, placenta and stomach. We have used RT-PCR to show that leptin mRNA is selectively transcribed in specific areas of rat brain and pituitary, and in a rat glioblastoma cell line. Using immunocytochemistry we have also shown leptin protein immunoreactivity in the corresponding tissues and cells, and confirmed this by Western blot using two epitope-specific antisera. Leptin mRNA expression in the hypothalamus is suppressed by fasting (48hr), suggesting a role for brain leptin in the central regulation of appetite. These data support the hypothesis that central nervous system derived leptin is a likely ligand for central leptin receptors.

Animals↗
PubMed1999

Epidemic and endemic seroprevalence of antibodies to Cryptosporidium and Giardia in residents of three communities with different drinking water supplies.

This study was carried out to compare cryptosporidiosis and giardiasis seroprevalence rates in residents of three communities. Community (Com 1) uses drinking water from deep wells, community 2 (Com 2) uses surface water from a protected watershed, and community 3 (Com 3) uses surface water frequently containing Cryptosporidium oocysts and Giardia cysts. Unfiltered drinking water from each community was collected at the tap and tested for Cryptosporidium oocysts and Giardia cysts during the 12 months in which sera were collected for testing. No oocysts or cysts were detected in the water from the Com 1 deep wells; oocysts and cysts were detected intermittently in the drinking water from the other two communities. A waterborne outbreak of cryptosporidiosis occurred in a municipality adjacent to Com 3 six months into this 12-month study. Sera from residents of each of the communities were collected proportionately by month and by population size. Coded sera were tested for IgG to Cryptosporidium using a previously developed Western blotting method. The presence or absence of bands at 15-17 kD and/or 27 kD was recorded for the 1,944 sera tested. Definite bands at 15-17 kD and/or 27 kD were detected in 981 (50.5%) of the sera. A total of 33.2% of sera from Com 1 (community using deep wells) were positive using the same criteria compared with 53.5% (Com 2) and 52.5% (Com 3) of sera from the two communities using surface drinking water. Both bands (15-17 kD plus 27 kD) were detected in 582 sera (29.9%) from the three communities: 14.1% of sera from Com 1 compared with 32.7% from Com 2 and 31.5% from Com 3. These findings are consistent with a lower risk of exposure to Cryptosporidium from drinking water obtained from deep well sources. However, analysis of results by calendar quarter showed a significant (P < 0.001) increase in the number of Com 3 positive sera (compared with Com 1) following the waterborne outbreak. Without this outbreak-related observation, a significant overall difference in seropositivity would not have been seen. We also observed that in sera from the community affected by the outbreak, the presence on immunoblots of both Cryptosporidium bands appeared to be the best indicator of recent infection. Seroprevalence rates using an ELISA to detect IgG to Giardia were estimated using the same sera. Overall 30.3% (590 of 1,944) of sera were positive by the ELISA. A total of 19.1% of sera from Com 1, 34.7% from Com 2 and 16.0% from Com 3 were seropositive. Rates for both Com 3 and Com 1 did not change significantly over time. In Com 2, rates decreased significantly (P < 0.001) during the last half of the study period (third and fourth calendar quarters). The reasons for the decrease in seroprevalence in Com 2 sera are presently not known. These studies show intriguing associations between seroprevalence, outbreak-related laboratory serologic data, and patterns of parasite contamination of drinking water. Further studies are required to validate the serologic approach to risk assessment of waterborne parasitic infections at a community level.

Animals↗
PubMed1999

[Correction of the secondary nasal deformities of the unilateral cleft lip and palate].

OBJECTIVE: To develop a new method to correct secondary nasanl deformities of cleft lip and palate. METHODS: Establishing the balance of maxilla on both sides, followed by varied procedures to correct anormaly of osseous-cartilagious framework of nose, and taking some of nasal-labial muscle to restore the continuity and balance of anterior facial expressive muscles. RESULTS: 78 cases were treated by this way and the result was satisfying. CONCLUSIONS: Imbalance of maxilla and anterior facial expressive muscle and anormaly of nasal framework should be repaired for correcting the nasal deformity of cleft lip and palate effectively.

Adolescent↗
PubMed1999

[Dynamic changes of neurotrophic factors in different cerebral areas after full cerebral ischemia and reperfusion in old rats].

OBJECTIVE: To explore the relationship between vascular dementia and nerve growth factor (NGF) and brain-derived neurotrophic factor (BDNF). METHODS: 42 male and female senile Wistar rats were randomized into control and experimental groups. The control group was subdivided into A, and C three groups and the experimental group into 6 subgroups, i.e 15 min of ischemia alone and ischemia combined with reperfusion of 1 h, 6 h, 2 d, 4 d and 9 d. Swimming maze was performed before and after operation. The contents of NGF and BDNF in different parts of brain were examined in different periods of ischemia and reperfusion with ABC method of immunocytochemistry. RESULTS: NGF expression in frontal lobes reached a peak level in 2 days after reperfusion and then disappeared quickly, that in parietal lobes showed a moderate level in 15 minutes of ischemia and reached a peak in 9 days of reperfusion. However, there is no expression in thalamus in early ischemia and reperfusion, but reexpression occurred after 2 days of reperfusion. BDNF expression showed a peak level after 2 days of reperfusion and then decreased in frontal lobes, but a high level of expression that was unchanged in parietal lobes and hippocampal areas. The increasing expression in thalamus occurred only 9 days after reperfusion. CONCLUSION: The distribution of BDNF was wider than that of NGF. There was a good protective action of NGF and BDNF in frontal lobes in the early period of ischemia with reperfusion and there existed persistent and prompt action of the neurotrophic factors in parietal lobes and hippocampal areas. The protective action of NGF in thalamus was poor, but that of BDNF was good.

Animals↗
PubMed1999

[Management of retrohepatic inferior vena cava injuries in hepatectomy for neoplasm].

OBJECTIVE: To evaluate the management of injured retrohepatic inferior vena cava during hepatectomy for neoplasm. METHODS: Step-by-step hepatic vascular exclusion, finger pressing, finger pinching, and surface-to-surface sewing up were used in the management of injured retrohepatic inferior vena cava in 16 cases of hepatic resection. RESULTS: In all cases, bleeding was stopped immediately after the procedure without any death and rebleeding. All cases survived after 6 - 18 month follow-up. CONCLUSIONS: The methods mentioned above are simple, useful, time-saving, safe and effective.

Adult↗
PubMed1999

[Intestinal blood perfusion improved by early enteral feeding in burned rat].

OBJECTIVE: To explore the mechanism of intestinal blood perfusion improved by early enteral feeding after burn injury. METHODS: Wistar rats were inflicted with 30% total body surface area full thickness flame burn and randomly divided into three groups: burned control (B), burned and early feeding (EF), and normal control (C). The content of endothelin (ET), nitric oxide (NO), vasoactive intestinal peptide (VIP), and intestine mucosal blood flow (IMBF) were determined at postburn 0, 3, 6, 12, 24, 48 hours. RESULTS: The content of ET, NO, VIP in small intestine as well as the ratio of ET/NO, ET/VIP were increased significantly and the IMBF was decreased markedly postburn. In EF group, ET, ET/NO and ET/VIP were significantly lower (P < 0.05, P < 0.01), and NO, VIP as well as IMBF were higher than those in B group (P < 0.05, P < 0.01). There were negative correlation between ET/NO, ET/VIP and IMBF (r(1) = -0.95, P < 0.01; r(2) = -0.87, P < 0.01). CONCLUSIONS: The mechanism of intestinal blood perfusion improved by early enteral feeding may be correlated with increased NO, VIP and decreased ET induced by foods stimulating intestinal nerve.

Animals↗
PubMed1999

[Anaerobic infection and its rapid detection in surgical patients].

OBJECTIVE: To investigate anaerobic infection and its rapid detection in surgical patients. METHODS: 372 specimens were collected from surgical patients for anaerobe detection. To find a rapid detectable method, 110 specimens were collected for comparative studies by using indirect immunofluorescent antibody technique (IFA), enzyme labeled antibody technique (ELAT) and general cultural method (CM). RESULTS: The isolation rate of anaerobes was rather high in pyothorax (88.9%), abdominal abscess (86.7%), appendicitis (83.9%) and cerebral abscess (all five cases were positive). In burn wounds, the rate was about 23.6% especially in deep burn wounds. Among 212 strains detected, the predominant anaerobes were as follows B. melaninogenicus (28.8%), B. fragilis (25%), F. nucleatum (7.5%), C. perfringens (7.5%), and peptostreptococcus (5.7%); most of them (87.8%) were non-sporing anaerobes. Mixed infection with aerobes accounted for 64%. The survey of rapid detection was conducted in B. fragilis, B. melaninogenicus, C. perfringens, F. nucleatum and peptostreptococcus. The detectable rate was higher in IFA (79.1%) and ELAT (80.9%) than in CM (37.3%). CONCLUSION: IFA and ELAT might be rapid, specific, sensitive, and simple for detecting anaerobes.

Abdominal Abscess↗
PubMed1999

[The expression of IGF-I, TGF beta and Fas-L in granulosa cells of ovarian follicle with relation to the onset of atresia in rats].

This study was designed to investigate the effects of IGF-I, TGF beta and Fas-L on the sustaining of granulosa cells of ovarian follicle and the modulation of apoptosis of those cells, and to understand the molecular mechanisms of ovarian follicle atresia. Paraffin-embedded sections of SD rat ovary were made. Both TUNEL method and PCNA immunohistochemistry were employed to recognize atretic and healthy follicles. The expression of IGF-I, TGF beta, Fas-L and their receptors was displayed by immunostaining. The results showed that most of the granulosa cells within the healthy preantral and antral follicles were PCNA(+). At the early stage of atretic antral follicle, more than 5 granulosa cells were labelled by TUNEL method, and some granulosa cells were PCNA(+). At the late stage of atretic antral follicle, were labelled by TUNEL method. The immunoreactive products of IGF-I, IGF-IR, TGF beta, TGF beta R, Fas and Fas-L could be seen in the granulosa cells of healthy antral follicles. But, Granulosa cells were only TGF beta, TGF beta R and Fas immunopositive in all atretic antral follicles. In conclusion, combination of TUNEL method and PCNA immunochemistry is of benefit for distinguishing atretic follicles from healthy follicles. IGF-I might play an important role in stimulating proliferation of the granulosa cells and sustaining them. The lower expression or disappearance of IGF-I in the antral follicle might cause the onset of atresia. TGF beta, Fas-L and Fas might mediate apoptosis of the granulosa cells in antral follicles, causing follicle atresia. But, their effects of mediation could be inhibited as IGF-I exists in the follicles.

Animals↗
PubMed1999

[A study on nasal absorption of psoralen and isopsoralen in Psoralea corylifolia L].

OBJECTIVE: To investigate the nasal absorption regularities of psoralen and isopsoralen of different concentrations. METHOD: Building an experimental model of rat in situ nasal recirculation and determining the contents of psoralen and isopsoralen by HPLC. RESULT: The nasal absorption of psoralen and isopsoralen fitted in with zero order kinetics, getting saturated with the increase of concentration. CONCLUSION: A suitable concentration is necessary for the preparation of nasal remedies psoralen and isopsoralen.

Absorption↗
PubMed1999

[Effect of transforming growth factor-beta on proliferation cycle of epiphyseal chondrocyte].

In order to investigate the effect of transforming growth factor-beta (TGF-beta) on chondrocyte proliferation cycle, we used flow-cytometry to assess the epiphyseal chondrocyte of embryonic chick femora which was cultured in free-serum media and treated with TGF-beta. The results showed that after treated with TGF-beta for 24 h, the proliferation indexes(PIs) of experimental groups(0.11 ng, 0.33 ng, 1.00 ng/ml) were lower than the PIs of the control groups, but the PI of 3.00 ng/ml group was higher than that of the control group (P < 0.001). After treated for 48 h, except the 0.11 ng/ml group, the PIs of experimental groups were lower than those of the control (P < 0.001). And after treated for 96 h, the PIs of all groups were higher than those of the control; the PI of the 0.33 ng/ml group was the highest (P < 0.001). These suggest that after treated in varied time and dosage, the effect of TGF-beta on epiphyseal chondrocyte is obvious, and TGF-beta on epiphyseal chondrocyte is obvious, and TGF-beta can inhibit chondrocyte proliferation first, and then its effect on chondrocyte can transform from inhibition into proliferation.

Animals↗
PubMed1999

[Applications of porous polymeric materials and its biocompatibility].

With the barrier materials, guided tissue regeneration materials and hybrid artificial organs as the representafive materials, the applications of polymer skeletal materials in biomedical fields are introduced in this paper. Based on the results of the induced carcinoma, collagenous encapsulation and chronic inflammation around implanted polymers, the effects of polymers topography on biocompatibility are discussed, and the importance of topographical compatibility of materials is emphasized.

Biocompatible Materials↗
PubMed1999

[Development of continuous rat infusion device].

In order to perform better scientific researches on fluid resuscitation, total parenteral nutrition and continuous drug administration in rats, we developed a set of rat infusion device. The device, the characteristics of reasonable design, simple operation, low cost, good practicability, and making it by oneself or buying a whole set, can not only assure rats to run around, drink water, eat food freely, but also insure continuous infusion and drug administration during the experimental study of rats.

Animals↗
PubMed1999

[Instrumental analysis and systematic investigation on heavy oils from coal. I. Analysis of hydrocarbon class composition].

A study on the analysis of hydrocarbon class composition was carried out by thin layer chromatography with flame ionization detection(TLC/FID). The optimum analytical conditions, experimental reproduction, standard deviation, quantitative correction factors of hydrocarbon class and so on were investigated. The instrument used were Mark III, LATROSCAN TH-10 analyzer, thin layer rod was a CHROMAROD silica rod(150 mm x 0.9 mm i.d). A satisfactory TLC/FID analytical method was established after a series of experiments and investigation. Typical heavy oils from coal were investigated based on this method. The optimum conditions were that the flame ionization detector was operated at a hydrogen flow rate of 100 mL/min corresponding to 90 kPa and air flow rate of 1.9 L/min. The determinations in groups of saturated hydrocarbons, aromatics, resins and asphaltenes were performed by using n-heptane, toluene and V(chloroform):V(methanol) = 95:5 as developing solvents. The developing distances were controlled at 10 cm, 5.5 cm and 2.5 cm respectively. In the present paper qualitative and quantitative analysis have been studied. And the method established was sufficiently applied to determine heavy oils from coal of coking plants of Shanxi.

English Abstract↗