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Biomedical subjects

A Li

Publications and source records attributed to A Li.

At least 289 records · Page 16Linked to original sources
PubMed1993

Estimation of the calorie requirements of burned Chinese adults.

Studies of energy expenditure in 75 adult Chinese patients with burns covering between 5 and 98 per cent of the total body surface area (TBSA) gave the following formula for an optimal nutritional regimen: the daily calorie input should be 1000 x m2 (surface area) + 25 x per cent TBSA. Glucose should provide between 55 and 60 per cent of the calories, fat between 20 and 30 per cent, and protein between 15 and 20 per cent. The calorie to nitrogen ratio should lie between 150 and 170 to 1.

Adolescent↗
PubMed1993

Retrotrapezoid nucleus glutamate receptors: control of CO2-sensitive phrenic and sympathetic output.

In decerebrate cats, we asked whether endogenous glutamate in the region of the retrotrapezoid nucleus (RTN) was involved in the control of CO2-sensitive phrenic and phrenic-related sympathetic output and, if so, which type of glutamate receptor was predominant. We made unilateral 10-nl injections into the RTN of the nonspecific glutamate receptor antagonist kynurenic acid (100 and 250 mM), the N-methyl-D-aspartic acid (NMDA) receptor antagonist 2-amino-5-phosphonopentanoic acid (AP5; 1 and 10 mM), the non-NMDA receptor antagonist 6-cyano-7-nitroquinoxaline-2, 3-dione (CNQX; 1 and 10 mM), and the inactive kynurenic acid analogue xanthurenic acid (100 mM). Each antagonist resulted in a significant dose-dependent decrease in the amplitude of the integrated phrenic nerve signal (PNA) over 30 min (CNQX > AP5 > kynurenic acid). The duration of the phrenic cycle was also decreased because of a shortening of expiratory time (CNQX > kynurenic acid > AP5). All three antagonists significantly decreased the initial slope of the PNA response to increased CO2 by 70-80% with no clear distinction in efficacy. The amplitude of the respiratory-related integrated cervical sympathetic nerve signal (SNA) was significantly decreased after kynurenic acid and CNQX but not AP5. In each case, the decrease in respiratory-related SNA accompanied a decrease in PNA and, at high levels of CO2, the decrease in respiratory-related SNA was greater than that of PNA. Endogenous glutaminergic input to neurons in the RTN via both NMDA and non-NMDA receptors is involved in the control of eucapneic PNA and timing, PNA-related SNA, and the response to increased CO2.

2-Amino-5-phosphonovalerate↗
PubMed1993

Widespread sites of brain stem ventilatory chemoreceptors.

We produced local tissue acidosis in various brain stem regions with 1-nl injections of acetazolamide (AZ) to locate the sites of central chemoreception. To determine whether the local acidosis resulted in a stimulation of breathing, we performed the experiment in chloralose-urethan anesthetized vagotomized carotid-denervated (cats) paralyzed servo-ventilated cats and rats and measured phrenic nerve activity (PNA) as the response index. Measurements of extracellular brain tissue pH by glass microelectrodes showed that AZ injections induced a change in pH at the injection center equivalent to that produced by an increase in end-tidal PCO2 of approximately 36 Torr and that the change in brain pH was limited to a tissue volume with a radius of < 350 microns. We found AZ injections sites that caused a significant increase in PNA to be located 1) within 800 microns of the ventrolateral medullary surface at locations within traditional rostral and caudal chemosensitive areas and the intermediate area, 2) within the vicinity of the nucleus tractus solitarii, and 3) within the vicinity of the locus coeruleus. Single AZ injections produced increases in PNA that were < or = 69% of the maximum value observed with an increase in end-tidal PCO2. We conclude that central chemoreceptors are distributed at many locations within the brain stem, all within 1.5 mm of the surface, and that stimulation of a small fraction of all central chemoreceptors can result in a large ventilatory response.

Acetazolamide↗
PubMed1993

Neurophysiologic study of beta-thalassemia patients.

Neurophysiologic investigations were performed in 34 Chinese patients with beta-thalassemia major maintained on long-term desferrioxamine treatment to look for subclinical toxicity in the auditory, visual, peripheral, or central neural pathways. In the auditory pathway study, four patients (12%) had mild sensorineural hearing impairment. Two patients (6%) had increased P 100 latencies in the visual evoked potential study, and nine patients (26%) had abnormal electroretinogram results. All had normal electrooculograms. Ophthalmoscopic examination was abnormal in three patients (9%), and three (9%) had a visual field defect. In the peripheral or central nervous pathways, seven patients (21%) had sensory neuropathy, of which three cases were probably related to diabetes mellitus. All had normal motor conduction velocities. Four patients (12%) had increased cortical latencies of median or posterior tibial somatosensory evoked potential. Abnormalities in multiple neural pathways were seen in four patients (12%). There was a significant association between subclinical toxicity to the peripheral or central nervous systems and serum ferritin level (P < .03) and the presence of diabetes mellitus (P < .002). There was no significant relationship between the age, dosage, or duration of desferrioxamine used and the increased risk of neurotoxicity to the auditory, visual, peripheral, or central nervous systems. There was also no association between the risk of neurotoxicity and the serum zinc, copper, or fructosamine levels.

Adolescent↗
PubMed1993

Serum antibody responses against shigella lipopolysaccharides and invasion plasmid-coded antigens in shigella infected Swedish patients.

Serum antibody responses to shigella lipopolysaccharide (LPS) and invasion plasmid-coded antigens (Ipa) were studied in 74 Swedish patients with culture verified bacillary dysentery using class-specific enzyme immunoassay (EIA). Anti-LPS responses were found in 80% and 79% serum samples, respectively, from S. flexneri and S. sonnei infected patients and anti-Ipa responses in 60% and 43%, respectively. The mean anti-Ipa IgG antibody titres in S. flexneri infected patients remained high for 4-6 months after onset while the anti-LPS IgG antibody titres had dropped to normal levels. The specificity of EIA for shigella Ipa was 90% and for S. dysenteriae, S. flexneri and S. sonnei LPSs it varied between 84% and 90%. No close correlations between the anti-LPS and anti-Ipa antibody responses were observed indicating that they may be differently regulated. The dynamics of the serum antibody responses indicates that an anti-LPS response is a good indicator of a recent shigella infection and an anti-Ipa IgG response a good indicator of a previous infection.

Adult↗
PubMed1993

Effects of tetrandrine on functions and ultrastructure of alveolar macrophages in smoke inhalation-injured rabbits.

A rabbit model with severe smoke inhalation injury was used to explore the effects of tetandrine (Tet) on the release of inflammatory mediators and the level of [Ca2+]i in alveolar macrophages (AM) as well as on the ultrastructural changes. It was found that Tet reduced the number of white blood cells (WBC) in bronchoalveolar lavage fluid, inhibited the release of LTB4 and O2-. from AM, and increased the [Ca2+]i in AM. The changes in size, pseudopod, and lysosome evacuation in AM treated with Tet were smaller than those in the AM from the untreated. These results suggest that Tet may alleviate the pulmonary injury through inhibiting the activation of AM.

Alkaloids↗
PubMed1993

A strain of urease negative Cryptococcus neoformans isolated from the environment in China.

This is the first report of a strain of urease negative Cryptococcus neoformans isolated from the environment in China. The colonies of this isolate showed brown pigmentation on cornmeal agar with 300 micrograms/ml caffeic acid, but failed to hydrolyze urea. Microbiological identification and pathogenicity tests in mice confirmed this as a strain of C. neoformans. A similar strain had reportedly been isolated from an AIDS patient.

Animals↗
PubMed1992

Neurotrophic activity of interphotoreceptor matrix on human Y79 retinoblastoma cells.

A neurotrophic activity of adult monkey and bovine interphotoreceptor matrix (IPM) was examined by using cultured human Y79 retinoblastoma cells as a model system. The cells were stimulated for 7 days in suspension culture with soluble IPM components and then attached to poly-D-lysine substratum. IPMs from both species induced greater than 80% neuronal differentiation of Y79 cell aggregates after 11 days of attachment as adjudged morphologically by the extension of lengthy, neurite-like processes. Immunocytochemical studies indicate that differentiated Y79 cells had an increased level of expression of neuron-specific enolase and a concomitant decreased expression of glial fibrillary acidic protein. This neurotrophic activity cannot be ascribed to nerve growth factor, platelet-derived growth factor, fibroblast growth factor, epidermal growth factor, or transforming growth factor beta. Although the nature of the factor and its cellular source have yet to be characterized, it may be related to a recently described neurotrophic protein secreted by human fetal retinal pigment epithelial cells in culture. Our findings provide evidence supporting the neuroblastic potential of the Y79 cell line and indicate that the IPM contains a potent neurotrophic activity. Such factors may be important to normal differentiation and maintenance of function of the neural retina.

Animals↗
PubMed1992

Excitotoxin induction of ornithine decarboxylase in cerebral cortex is reduced by phospholipase A2 inhibition.

The enzyme ornithine decarboxylase (ODC) has been shown to be induced by a number of conditions such as cold-injury, kindling, ischaemia and excitotoxin injection. In previous studies we have characterised the cortical response to kainate injection into the nucleus basalis and shown a substantial increase in both ODC mRNA and enzyme activity which reaches a maximum at 8h. This response is completely prevented by treatment with MK-801, indicating the involvement of NMDA receptors in mediating this response. Whilst NMDA receptors are known to gate a cation channel leading to increased calcium entry, an additional effect on the release of arachidonic acid has been reported. The possibility that NMDA receptor mediated activation of phospholipase A2 and release of arachidonic acid might mediate this ODC response was investigated in this study by treatment with the phospholipase inhibitors quinacrine and dexamethasone. Treatment of animals with quinacrine (100 mg/kg) at the time of injection of kainate into the nucleus basalis caused a significant attenuation of the induction of ODC in cerebral cortex of 43%. No further attenuation was seen at higher doses. A similar reduction in ODC induction was seen after treatment with dexamethasone (1 mg/kg) but a greater effect could be obtained (65% attenuation) at higher doses. The possible involvement of arachidonic acid derivatives in mediating ODC induction was further investigated by treatment with the cyclo-oxygenase inhibitor indomethacin and the lipoxygenase inhibitor nordihydroguaiaretic acid (NDGA). Indomethacin was able to significantly attenuate the induction of ODC (greater than 60%) whilst NDGA (30 mg/kg) was ineffective. These results indicate the possible role of arachidonic acid derivatives in the regulation of the expression of ODC in cerebral cortex after excitotoxin injection.

Animals↗
PubMed1992

Safety and immunogenicity of the live oral auxotrophic Shigella flexneri SFL124 in volunteers.

The live, aromatic dependent Shigella flexneri Y vaccine strain SFL124, with a deleted aroD gene, was tested for safety and immunogenicity in 21 healthy adult volunteers. A single dose of 2 x 10(9) live bacteria was given orally to ten volunteers, whereas 11 received three doses every other day. The vaccine was excreted for 4.2 days and was well tolerated by 90.5% of the vaccinees. Only 2 of 21 (9.5%) after the first dose had a self-limiting diarrhoea lasting 1 day; of volunteers given one dose only 3 of 10 showed anti-lipopolysaccharide (LPS) and anti-invasion plasmid coded antigen (Ipa) responses in serum. A faecal antibody response to LPS and Ipa was seen in six and three persons, respectively. Volunteers given three doses reacted with serum anti-LPS (9/11) and anti-Ipa (5/11) antibody responses. In stool, anti-LPS and anti-Ipa responses were detected in nine and eight volunteers, respectively. A booster dose of 2 x 10(9) bacteria given to six volunteers in the three-dose group 9-10 months later elicited high stool sIgA responses, indicating a strong mucosal memory, and was accompanied by a short excretion period of SFL124 (1.8 versus 4.2 days, p less than 0.05). The vaccination also elicited antibody-secreting cell (ASC) responses against LPS in peripheral blood: the three doses of the vaccine resulted in a stronger response than did the single dose, while the booster dose elicited only a limited ASC response. Volunteers previously exposed to shigellae exhibited stronger anti-Ipa responses in serum and stool suggestive of an immunological memory to the Ipa. The results indicate that SFL124 is a safe live vaccine strain inducing specific immune responses against LPS and Ipa with a mucosal immune memory lasting for at least 9 months.

Administration, Oral↗
PubMed1992

Dynamic balance changes between elastase and antiprotease in the early stages after smoke inhalation injury.

Following the use of a rabbit smoke inhalation injury model established in this institute, there were marked reductions in elastase activities in neutrophils and alveolar macrophages; rapid increases in elastase activity in broncho-alveolar lavage fluid (BALF); reductions of serum trypsin inhibitory capacity; a decrease of Pao2 and an increase of PaCO2, and marked increases of lung water volume. Significant correlations were found between the increased extravascular lung water content and the rising elastase activity in BALF. It seems probable that the imbalance between elastase and antiprotease played an important role in the development of acute lung injury after smoke inhalation.

Animals↗
PubMed1992

Clinical observations and methods for identifying the existence of cultured epidermal allografts.

Thirty-two burned or plastic surgery patients were grafted with allogeneic cultured epidermis on autograft donor sites. Two techniques, the indirect enzyme conjugated Staphylococcus Protein A assay with monoclonal antibodies against A or B blood group antigens and the polymerase chain reaction to detect a Y chromosome-specific DNA sequence, were employed to identify the presence of cultured epidermal allograft based on different ABO blood grouping or sex between donor and recipient. The methods have the advantage of high sensitivity and specificity in identifying the existence of allogeneic skin cells in grafts. The results indicated that the survival time of cultured epidermal allograft was prolonged up to 35 days. In addition, the intact coverage on some grafting sites may be composed of both host and donor origin cells, after about 3 weeks postgrafting.

Adolescent↗
PubMed1992

Clinical studies on postburn multiple organ failure: its aetiological factors and monitoring.

This study demonstrated that multiple organ failure (MOF) developed in 16 of 57 severely burned patients (28.1 per cent). When expressed as a percentage of the 590 patients admitted during the same period, the incidence became 2.7 per cent. Fifteen of the 16 MOF cases died, with a mortality of 93.8 per cent. In those patients with TBSA over 80 per cent with inhalation injury, severe shock and systemic infection, the incidence of MOF was significantly higher. Systemic infection and severe shock were the most important complications. These results indicated that the severity of the burn is the prime prerequisite of MOF, while severe shock and systemic infection are secondary but very important factors in the genesis and development of postburn MOF. The circulatory platelet aggregate ratio (CPAR) started to decrease significantly at 12 h postburn, remaining at low levels and declining further at 5-7 days postburn. However the values of the myocardial enzyme spectrum (MES) remained at significantly higher levels, indicating significant and continuous increases of microaggregate formation and the continuous existence of visceral and tissue ischaemia and cellular destruction. Changes of CPAR and MES in MOF patients were directly related to the development of MOF. It is advisable to use CPAR and MES to monitor the possible development of postburn MOF.

Adult↗
PubMed1992

The effect of tolbutamide on burn hypermetabolism.

The effect of tolbutamide on improving burn hypermetabolism was studied prospectively in 31 burn adults with total body surface area burned > 40 per cent and 18 burned rabbits immediately after burn injury to postburn day 10. The results showed that burn hypermetabolism could be reduced using tolbutamide, which may be the result of the correction of relative insulin insufficiency, tissue insulin resistance and improving glucose utilization.

Adult↗
PubMed1992

Roles of thromboxane and prostacyclin in the pathogenesis of acute respiratory failure in burn patients combined with inhalation injury.

Forty-one severely burned patients were divided into inhalation injury and non-inhalation injury groups. It was found that in the inhalation injury group, TXB2 level and TXB2/6-keto-PGF1 alpha ratio in both plasma and lung tissues were significantly elevated, circulatory platelet aggregate ratio markedly decreased, and blood viscosity greatly increased. Histopathologically, congestion, oedema, haemorrhage and thrombosis were observed in lung tissues taken from patients succumbing to respiratory failure. The changes in TXB2 and TXB2/6 keto-PGF1 alpha ratio accorded with the clinical course of the development of respiratory failure in burn patients with inhalation injury. It is proposed that the imbalance of TXA2/PGI2 plays an important role in the pathogenesis of respiratory failure in severely burnt patients complicated with inhalation injury.

Acute Disease↗