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Biomedical subjects

X J Yu

Publications and source records attributed to X J Yu.

At least 91 records · Page 5Linked to original sources
PubMed1990

Sequence of two alleles responsible for Gaucher disease.

Enzymatically amplified RNA transcripts were used to analyze the full coding region of the glucocerebrosidase gene from Gaucher disease patients. Two previously undescribed mutations were identified. One mutation consists of a single-base substitution in three different codons: codon 444, Leu (CTG) to Pro (CCG); codon 456, Ala (GCT) to Pro (CCT); and codon 460, Val (GTG) to Val (GTC). This mutant is called "pseudo pattern" (psi) because it is identical in sequence to a small region of the pseudogene in exon 10 (Horowitz et al., 1989). The other new mutation is a single-base substitution (C to T) resulting in the substitution of Cys for Arg in codon 463. These mutations in the human gene were duplicated in wild-type cDNA and expressed in 3T3 cells. The human mutant proteins were isolated by immunoaffinity and shown to have altered enzymatic properties demonstrating the causality of these two allelic mutations for Gaucher disease.

Amino Acid Sequence↗
PubMed1990

Polypeptides constituting the antigenic basis for identification of Rickettsia sibirica species by the standard serotyping method for spotted fever group rickettsiae.

The antigens of Rickettsia sibirica, Rickettsia rickettsii, and Rickettsia conorii were examined by Western immunoblots and the standard immunofluorescent serotyping assay with mouse anti-Rickettsia sibirica serum that is used for determining the species identification of spotted fever group rickettsiae. Serum was employed prior to absorption and after absorption with purified native or heated Rickettsia sibirica. The unabsorbed antiserum, the antiserum absorbed with heated Rickettsia sibirica and the antibodies eluted from native Rickettsia sibirica recognized two antigenic polypeptides of Rickettsia sibirica (130 and 118 kDa), Rickettsia rickettsii (151 and 133 kDa), and Rickettsia conorii (136 and 113 kDa), respectively when examined in native state, not denatured by heat. The antiserum absorbed with native Rickettsia sibirica reacted most strongly with one polypeptide of Rickettsia sibirica (118 kDa), Rickettsia rickettsii (133 kDa), and Rickettsia conorii (136 kDa); at the endpoint of the immunofluorescence assay there was minimal reactivity with the 130 kDa polypeptide by immunoblotting. Both Western immunoblots and immunofluorescence assay showed that the antiserum absorbed with native Rickettsia sibirica reacted with homologous and heterologous antigens at a much lower titer than did the antiserum that was not absorbed. However, the titers of reaction with Rickettsia sibirica, Rickettsia rickettsii, or Rickettsia conorii were not diminished by absorption of the native antiserum with heated Rickettsia sibirica. The antibody eluted from native Rickettsia sibirica reacted by immunofluorescence with all the rickettsiae at a higher dilution than the antibody eluted from heated Rickettsia sibirica.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1990

[Classification and treatment of fracture of the tibial plateau].

Classification of fracture of the tibial plateau and the results of treatment of 30 cases are as follows. Type 1, One or both condylar fracture without displacement or if any, it is less than 5 mm and with a depression less than 2 mm. 6 of 8 cases with this kind of fracture were handled non-operatively, and the remaining 2 operatively, open reduction and internal fixation. All the 8 patients (100%) got excellent or good results. Type 2, One or both condylar fracture with displacement and depression less than 10 mm each. 12 patients had this type of injury which was reduced by poking and fixed with bolt or wire. 95.83% of the patients got excellent or good results. Type 3, Comminuted fracture of one or both condyles associated with unstable Fracture of upper tibia. 7 of 10 cases having this sort of fracture were reduced by poking reduction with or without bone grafting and fixed with grooved angle plate. Result of the 7 patients (100%) was excellent or good. While the other 3, their operations were delayed because of local condition. The operative procedures were same except for fixation either with pins or Kirchner's wire. The results of these 3 patients were excellent or good in 85.19%. We feel that the favourable time for operation is within the first week after trauma; perfect reduction, rigid fixation and early motion of the joint are essential for expected outcome.

Adolescent↗
PubMed1989

Neuronal and glial changes in the rat phrenic nucleus occurring within hours after spinal cord injury.

The present study describes specific morphological changes in the normal ultrastructure of the rat phrenic nucleus which occur within 4 hours after an ipsilateral spinal cord hemisection rostral to the nucleus. Phrenic neurons were identified at EM levels by retrograde HRP labeling. Ultrastructural features of the phrenic nucleus in uninjured animals and at 4 hours and 1, 2, and 4 days after injury were qualitatively analyzed and then quantitated with a computerized morphometric system. Our results indicated that by 4 hours posthemisection, there was a significant increase in the number of double synapses. Furthermore, the number of double synapses remained significantly higher than normal at all the other posthemisection periods. A significant increase in the length of dendrodendritic membrane appositions was also noted as early as 4 hours posthemisection. The mean normal appositional length of 1.42 +/- 0.09 microns increased to 1.89 +/- 0.12 microns at 4 hours and further increased to 2.20 +/- 0.20 microns by 1 day posthemisection. The increase in the length of membrane appositions was most likely due to an active retraction of astroglial processes from their normal position in between the dendrites. Although there was an increase in the mean length of the dendrodendritic appositions, the mean percentage of the appositions (expressed as the total number of appositions divided by the total number of dendrites in each sample) was not increased significantly over normal values during the early posthemisection periods. By 2 and 4 days posthemisection, however, the percentage of dendrodendritic appositions increased to significantly higher values than normal. Normally, 4.68 +/- 0.69% of the dendrites in the phrenic nucleus were found to be in apposition, and this number increased significantly to 7.27 +/- 1.06% by 2 days and 7.46 +/- 0.79% by 4 days posthemisection. At these later posthemisection periods, the mean length of the appositions decreased to levels which were no longer significantly higher than normal. A distribution analysis of the length of each dendrodendritic apposition in both the normal and spinal hemisected rats showed that there were more dendrodendritic appositions in the phrenic nucleus at the later posthemisection periods. It also showed that their mean length was decreased because many of the new appositions were relatively short. The above neuronal and glial alterations of the phrenic nucleus have never before been described as a response to injury of the mammalian spinal cord. Furthermore, the possibility that the above changes could represent the morphological substrate for the unmasking of functionally ineffective synapses in ou

Animals↗
PubMed1989

[Studies on the origin of different discharge pattern of the two types of phrenic motoneurones by cross-correlation analysis].

Experiments were performed on twenty five anesthetized, paralyzed, vagotomized and artificially ventilated rabbits. Discharges of single phrenic nerve fibers were recorded. According to their discharge patterns, phrenic motoneurones were divided into two types: tonic units (TU) and phasic units (PU). A cross-correlation analysis was done between TU and TU, PU and PU, or TU and PU. In 21/36 pairs of phrenic motoneurones, the cross-correlation histogram showed a significant central peak, which represented synchronization of the pair of units resulting from a common input. There were three types of synchronization: short-term, broad peak and high frequency-oscillatory synchronization. The difference in synchronization number between heterogeneous pairs (1 TU and 1PU, 2/10 showing synchronization) and homogeneous pairs (2 TU or 2 PU, 19/26 showing synchronization) was statistically significant (x2-test, P less than 0.05). These results suggest that TU and PU have different central inputs, which result in their different discharge patterns between the TU and PU.

Animals↗
PubMed1988

Antigenic analysis of Chinese strains of spotted fever group rickettsiae by protein immunoblotting.

Protein immunoblotting demonstrated that 6 Chinese strains of spotted fever group (SFG) rickettsiae from northern China had antigenic polypeptides identical to those of Rickettsia siberica (strains 246 and 232), and dissimilar to other SFG rickettsiae. The various species of other SFG rickettsiae exhibited serologically distinct epitopes as well as many cross-reactive epitopes in protein immunoblotting. All SFG rickettsiae examined in this study had major antigenic polypeptides of 113-160 kDa.

Animals↗
PubMed1986

Thrombin purification by one-step preparative affinity chromatography on modified polystyrenes.

Insoluble polystyrenes substituted with sulphonate and L-arginyl methyl ester have been synthesized. Using their specific affinity for thrombin, we developed a simple one-step chromatographic procedure for thrombin purification. As a control, insoluble polystyrenes substituted only with sulphonate groups were tested. The results obtained confirmed the importance of the arginyl residues grafted onto these polymers to obtain an affinity matrix useful for purifying thrombin with a high specific activity and a good recovery.

Chromatography, Affinity↗
PubMed1986

High-performance affinity chromatography of human thrombin on modified polystyrene resins.

Cross-linked polystyrenes modified with L-arginyl methyl ester mimic the binding site of antithrombin III and thrombin substrates. They can be used as stationary phases in high-performance affinity chromatography of thrombin. Under isocratic conditions, thrombin is strongly adsorbed on the resins when the sodium chloride concentration is lower than 0.5 M. The bound enzyme can be selectively desorbed when the salt concentration is raised to about 1.2 M. With a linear salt gradient, the specific elution of thrombin can be effected with a high recovery of its enzymatic activity. The decomposition products of thrombin, when treated with sodium dodecyl sulphate, are not retained by the stationary phase. The effects of the flow-rate and salt gradient slope on the adsorption and desorption of alpha-thrombin demonstrate the importance of kinetic parameters.

Adsorption↗
PubMed1986

Affinity chromatography of thrombin on modified polystyrene resins.

Insoluble polystyrenes substituted with sulphonate and L-arginyl methyl ester (PAOM) present substituents mimicking the reactive binding site of antithrombin III. These materials have a specific affinity for thrombin. The binding of the enzyme is reversible and the eluted thrombin remains active. Consequently, these resins can be used as stationary phases in affinity liquid chromatography in order to purify thrombin with a high biological activity. The influence of different characteristics of such polymers (substitution ratio, average particle size, affinity constant, synthesis conditions) on the purification performance is studied. Human prothrombin complex concentrate is activated and applied onto the gel. A purified human thrombin of high specific activity is separated with a high recovery of biological activity of the enzyme.

Chromatography, Affinity↗
PubMedDate not supplied

Dual infection with Ehrlichia chaffeensis and a spotted fever group rickettsia: a case report.

Well-documented cases of simultaneous human infection with more than one tick-borne pathogen are rare. To our knowledge only two dual infections have been reported: simultaneous human infection with the agent of human granulocytic ehrlichiosis and Borrelia burgdorferi and simultaneous human infection with B. burgdorferi and Babesia microti (1-2). Rocky Mountain spotted fever has long been known to be endemic in North Carolina; cases of human ehrlichial infection were recognized there soon after Ehrlichia chaffeensis was recognized as an important cause of tick-borne disease in the southeastern United States. Because both Rocky Mountain spotted fever and ehrlichiosis are prevalent in North Carolina, occasional cases of simultaneous human infection by rickettsial and ehrlichial agents would not be surprising; however, no such cases seem to have been reported.

Adult↗