Biomedical subjects

J L Liu

Publications and source records attributed to J L Liu.

At least 145 records · Page 8Linked to original sources

PubMed1990

The role of frontal neurons in pain and acupuncture analgesia.

To study the role of frontal neurons in pain and acupuncture analgesia, experiments were carried out on 4 monkeys (Macaca mulatta) during performing two tasks, the Heat Discrimination Response GO/NO-GO Task (Task I) and the Heat Delayed Discrimination GO/NO-GO Task (Task II). After a criterion of 90% of correct performances over three successive days had been reached, activity of single neurons was recorded from the frontal cortex. Of 276 Task I-related neurons, 211 responded to noxious and/or innocuous heat stimuli. Of 73 Task II-related neurons, 59 responded to noxious and/or innocuous heat stimuli. During acupuncture, the nociceptive reaction time for lever release to avoid painful stimuli was increased, the percentage of correct performances was lowered, and the neuronal responses to noxious and/or innocuous stimuli were suppressed. These neurons were mainly located in a circumscribed area medial to the superior ramus of the arcuate sulcus in frontal cortex, including the prefrontal and premotor areas. It is suggested that neurons in this area may be related to the discrimination of noxious and innocuous stimuli. The suppression of the activity of these neurons during acupuncture may be involved in the whole mechanism of acupuncture to facilitate the production of analgesia.

Acupuncture Analgesia↗

PubMed1990

[Observations on neuronal activity in frontal cortex and EMGs in monkeys during performing noxious and innocuous heat discrimination GO/NO-GO task].

To study the functional implication of neuronal responses in frontal cortex to noxious and innocuous heat stimuli, experiments were carried out on two monkeys (Macaca mulatta) during performing a delayed discrimination GO/NO-GO task. The animals were trained to hold a lever for at least 3 s in the response period when an innocuous heat stimulus had been applied to the forearm in the cue period, or release it within 1 s with a noxious one. After a criterion of 90% of correct responses in 3 successive days was reached, single neuronal activity was recorded from the frontal cortex along with EMGs from six muscles in both arms. Of 142 task-related neurons recorded, 87 (66.4%) were related to heat, 34 to visual, and 21 to both visual and heat stimuli. Among the heat-related neurons, 22 were responsive to noxious heat, 18 to innocuous heat, and 47 to both. Of the neurons responding to both noxious and innocuous heat stimuli, 4 neurons showed changes in discharge rates, depending on the type of stimuli. In most cases, muscular activities just appeared at the moment of lever pressing and/or releasing in m. extensor digitorium communis, m. flexor carpi ulnaris and m. flexor carpi radialis of the performing arm. No regular muscular activities appeared in other muscles and in other periods of the task. The result showed that the neuronal responses in frontal cortex elicited by heat stimuli in the cue period were not related directly to the initiation and modulation of behaviours.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed1989

Acute femoral neck fracture in children--preliminary report.

Nineteen children, aged 3-15 years, with acute femoral neck fracture were treated. The follow-up period ranged from 2 years to 6 years, 9 months (avg. 54.8 +/- 14.5 months). The clinical and radiological assessments were carried out according to the assessment system of Ratliff. Undisplaced fractures and all intertrochanteric fractures were treated conservatively and displaced ones by reduction and multiple pinning. The outcomes reveal 14 (79%) with good results, 2 (10.5%), fair and 3 (15.8%), poor. Four hips (21%) developed avascular necrosis with 2 requiring secondary surgical procedures. Both of them also had leg length discrepancy. Another 3 hips (15.8%) developed coxa vara, one of them had mild leg length discrepancy.

Acute Disease↗

PubMed1989

Na,K-ATPase: comparison of the cellular localization of alpha-subunit mRNA and polypeptide in mouse cerebellum, retina, and kidney.

A clone encoding mouse brain Na,K-ATPase alpha-subunit was isolated from a mouse brain lambda gt11 cDNA library by using antisera to mouse and bovine brain alpha-subunit. A comparison of the nucleotide sequence of this clone with published sequences of rat brain alpha-subunit isoform clones showed it to be most similar to rat brain alpha 1. An RNA antisense probe prepared from the cDNA insert of the mouse clone detected a single mRNA of approximately 4.5 kb in Northern blots of mouse brain and kidney RNAs. This probe hybridized only to an alpha 1-cDNA insert from rat brain under high stringency conditions on Northern blots. The RNA antisense probe was used for in situ hybridization to sections of mouse kidney, cerebellum, and retina, and the cellular distribution of alpha-subunit mRNA (alpha-mRNA) was compared with that of alpha-subunit polypeptide (alpha-subunit) detected by immunofluorescence in similar sections. In kidney, alpha-mRNA distribution closely paralleled that of the polypeptide with abundant expression in ascending thick limbs and cortical distal tubules and weaker labeling in cortical proximal tubules. The co-distribution of alpha-mRNA and polypeptide in kidney where Na,K-ATPase localization is well established is consistent with the specificity of these probes. In the retina, prominent labeling with both probes was seen in photoreceptor inner segments, inner nuclear layer, and ganglion cell bodies. Plexiform layers and optic fibers expressed abundant alpha-subunit but little mRNA. Light labeling for both was seen in the outer nuclear layer. In cerebellum, alpha-mRNA and alpha-subunit were associated with soma of granule cells, basket cells, and stellate cells. Glomeruli and basket terminals contained abundant alpha-subunit but exhibited little reactivity with the riboprobe. In Purkinje cell bodies, in contrast, the antibody used to identify the cDNA clone did not resolve significant polypeptide in the somal plasmalemma despite abundant somal mRNA expression. Comparison of distribution of the two probes in cerebellum and retina indicates that message accumulation is primarily in cell bodies, while alpha-subunit epitopes may be co-expressed in cell bodies and/or transported to distant sites in cell-specific patterns.

Amino Acid Sequence↗

PubMed1989

[Functional plasticity of frontal neurons in rhesus monkeys during performing visual discrimination go/no-go task].

We previously reported that frontal neurons in monkeys may be essentially responsive to the biological meanings of the stimuli in a task, rather than to their physical attributes. To examine this hypothesis, activity of single neurons was recorded from the frontal cortex of monkeys (Macaca mulatta) while performing a visual delayed discrimination GO/NO-GO task (task I, n = 2) and a visual discrimination response GO/NO-GO task (task II, n = 2), respectively. A green or red light presented in the period 2 of task I and in the period 4 of task II was used as a cue to guide the monkeys' behaviour. The same green/red light was presented in the period 2 of task II as well, but this was not a cue and had no definite meanings in the task. The monkeys were trained to watch attentively the panel in period 3 of both tasks. A total of 163 task-related neurons were recorded: 98 in task I and 65 in task II. Although neuronal responses appeared in all periods of both tasks, the majority of the responses (70% of the total) were in the periods 2 and 3 of task I, and in the periods 3 and 4 of task II. Furthermore, in the period 2 of task I and period 4 of task II, but not in the period 2 of task II, most of neurons were responsive exclusively to either green or red light. The results support the hypothesis stated above, and suggest that the responses of the frontal neurons to signal stimulation are gradually established in the course of learning, and possess highly developed functional plasticity.

Animals↗

PubMed1989

[The role of sulfhydryls in indomethacin-induced gastric mucosal injury in rats].

The possible role of sulfhydryls in indomethacin-induced gastric mucosal injury was studied. No significant decrease of the contents of both non-protein and protein-binding sulfhydryls was observed in the gastric mucosa during injury. Indomethacin-induced gastric ulcer was inhibited by cysteamine of 132 and 264 mumol, i.g. or of 132 mumol, s.c. by 82%, 92% and 75% respectively. Such protective effect was not observed with cysteine in equal molar dose. Subcutaneously injected cysteamine (132 mumol) inhibited gastric acid secretion by 46% in indomethacin-treated rats, while no effect was observed on acid secretion when cysteamine was given intragastrically. Cysteamine, given through both routes, did not affect gastric barrier mucus secretion. It is suggested that sulfhydryls in gastric mucosa are not involved in the mechanism of indomethacin-induced injury and that the potent cytoprotective effect of cysteamine against indomethacin-induced ulcer maybe not caused by its sulfhydryl group.

Animals↗

PubMed1988

Metabolic changes in women using a long-acting monthly oral contraceptive and return of ovulation on discontinuation.

Metabolic changes were investigated in two groups of women using oral contraceptives for 5 to 16 years. Blood samples were taken during the last cycle of oral contraceptive use and three months post-treatment. One group had used a monthly oral contraceptive (MOC, 3mg quinestrol and 10mg 16-methylene chlormadinone acetate) and the second group a daily oral contraceptive (DOC, 35 micrograms ethynylestradiol and 0.625 mg norethisterone). During treatment there were increases in serum total cholesterol and triglycerides but not HDL-C, in plasma total cortisol but not in renin activity, angiotensin II or urinary free cortisol excretion, in hemoglobin and some coagulation factors but not Factor X or antithrombin III, platelet function or fibrinolysis. The area under the blood glucose concentration-time curve, but not that for serum insulin, was slightly increased and there was no change in fasting blood sugar concentrations. All metabolic parameters, except plasma cortisol, which had shown an increase on treatment, had decreased to control levels within 3 months. Ovulation returned promptly in all women, the mean time being 70 days for Group MOC and 44 days for Group DOC. Thus, in spite of the long duration of use of the oral contraceptives, metabolic changes were minor.

Adult↗

PubMed1988

Morphometric evidence for non-pressure-related arterial wall thickening in hypertension.

To investigate the relation of pressure and vascular wall thickening in hypertension, we coarcted the abdominal aorta upstream to the renal arteries in 14 rats. Sham-coarcted (n = 16) and two-kidney, one-clip (Goldblatt) hypertensive rats (n = 13) served as controls. Tail, femoral, and carotid arterial pressures rose (p less than 0.01) in the two-kidney, one-clip hypertensives; only carotid pressure rose (p less than 0.01) in the coarcted rats, tail and femoral pressures remaining normal (p greater than 0.25). Thus, the hindquarters of the coarcted rats remained normotensive. Four to six weeks after surgery we perfusion-fixed vascular tissues of the hindquarters, including kidneys, with formalin at in vivo levels of pressure. Glycol methacrylate-embedded tissues were sectioned at 1 micron thickness and vessels quantitatively evaluated. The outer medial and lumen perimeters of abdominal aorta, femoral artery, and renal arterioles were measured; from these measurements, vessel outer and lumen diameters, medial thickness, medial area, and medial thickness-to-lumen radius ratios were calculated. Compared with sham-coarcted rats, abdominal aorta, femoral arteries, and renal arterioles less than 61 microns outer diameter in rats with coarctation and Goldblatt hypertension had significantly increased (up to +100%) medial area, medial thickness, and medial thickness-to-lumen radius ratios. In general, magnitudes of abnormalities were similar in Goldblatt and coarcted rats. Renal arterioles greater than 60 microns outside diameter in Goldblatt hypertensive, but not coarcted, rats also were thickened. These results indicate that vascular wall thickening occurs in conduit arteries and smaller renal arterioles in the normotensive hindquarters of coarcted rats, providing morphometric evidence for non-pressure-related mechanisms involved in vascular growth in this form of hypertension.

Animals↗

PubMed1988