Biomedical subjects

Z Y Hua

Publications and source records attributed to Z Y Hua.

5 recordsLinked to original sources

PubMed1992

Correlations between an autoregressive model coefficient of the electromyogram of human jaw-closing muscles and maximum clenching time at the intercuspal position.

During maximum clenching in the intercuspal position, surface electromyograms of both masseters and both anterior temporales in seven healthy subjects with intact natural dentitions were sampled to generate a four-order, autoregressive model of the myoelectrical signal. The correlation coefficients and the linear regression between the model coefficients and the clenching time were calculated. The first-order autoregressive coefficient had the greatest negative correlation on average. In this model the first-order coefficient relates to muscular fatigue and the slope of the regressive equation relates to the length of time the isometric contraction can be maintained.

Adult↗

PubMed1992

Pancreatic phospholipase A2 in proximal tubules of rat kidney in experimental acute pancreatitis and after intravenous injection of the enzyme.

Kinetics and distribution of i.v. human pancreatic phospholipase A2 (h-PLA2) were determined in intact and nephrectomized rats, and tissue localization of rat pancreatic PLA2 (r-PLA2) was studied by immunohistochemistry in experimental acute pancreatitis. The concentration of h-PLA2 and the catalytic activity of phospholipase A2 in plasma decreased exponentially in intact and nephrectomized animals after the injection. The initial 15-min half-life was considerably longer in nephrectomized animals, and higher h-PLA2 concentrations and PLA2 catalytic activities were found in plasma. h-PLA2 was localized in endocytotic vesicles and apical cytoplasmic vacuoles in proximal tubule cells of the kidney. The intensity of the immunoreaction decreased considerably between 15 and 50 min in these cells. No signs of tubular damage were seen by light microscopy. Neither immunoreactive h-PLA2 nor PLA2 catalytic activity was found in urine. r-PLA2 was observed in proximal tubule cells 15 min after an injection of sodium taurocholate (necrotizing pancreatitis group) or saline (edematous pancreatitis group) into the pancreatic duct. Signs of tubular damage were present in necrotizing pancreatitis, but tubular morphology was normal in the animals with edematous pancreatitis. We conclude that the proximal tubule cells of the kidney participate in the metabolism of circulating pancreatic PLA2, and considerably higher PLA2 levels persist in plasma in nephrectomized animals. Endogenous pancreatic PLA2 is detected in kidneys in acute pancreatitis.

Acute Disease↗

PubMed1992

Relationship between autoregressive model coefficients of EMG and its potentials of jaw closing muscles at rest position and clenching.

At rest position and varied clenching levels at intercuspal position, autoregressive (AR) models of myoelectrical activities of both masseter and anterior temporal muscles of 11 healthy subjects with intact natural dentitions were established. The relationship between the AR model coefficients of surface EMGs and their potentials was analyzed by multiple linear regression. It was found that the fourth order coefficient of AR had the greatest effect on the EMG potential levels and their relationship was positive in all recorded muscles. The results indicate the AR coefficients may become a characteristic parameter to describe myoelectrical activity of jaw closing muscles.

Action Potentials↗

PubMed1991

A microcomputer system for collecting and processing physiological information about the masticatory system.

A software system has been written for IBM PC, XT, AT and compatible computers to be used for data collection, analysis and display. The system supports the sampling and processing of data for jaw movement tracks, myoelectrical activities of masticatory muscles, the temporomandibular joint (TMJ) and occlusal sounds and bite force, etc. The package includes the following functions: calculating displacement, velocity, curvature, and curvature center of jaw movement trace, analyzing myoelectrical signals in amplitude integration, root mean square and power spectrum, processing TMJ sounds and occlusal sounds and bite force, analysing jaw movement traces and myoelectrical activities during mastication simultaneously, determining the maxillomandibular relations, etc. The program also provides versatile formatting capability for video, printing and plotting of data, and graph creation. The most of the above programs have flexibility and adaptability to other physiological signal processes.

Bite Force↗

PubMed1989

Sotos syndrome with a balanced reciprocal translocation t(2;12)(q33.3;q15).

A balanced reciprocal translocation, 46,XY, t(2;12), was detected in a male infant who had the characteristic features of Sotos syndrome. His father's karyotype was normal, but his mother and an older brother had the same chromosomal abnormality without a history or clinical features of Sotos syndrome.

Chromosome Banding↗