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Biomedical subjects

H Guo

Publications and source records attributed to H Guo.

At least 253 records · Page 14Linked to original sources
PubMed1995

An extensive subfrontal approach to the lesions involving the skull base.

A modification of the transbasal approach of Dorome called extensive subfrontal approach and the surgical results with this approach in 22 cases are presented. Bilateral frontal craniotomies incorporated with the removal of orbital ridges and part of the orbital roofs were fashioned en bloc. It may give rise to good exposure of the midline lesions of the anterior, middle and posterior skull base, minimizing the need for the retraction of frontal lobes. There was no surgical mortality in this series of cases. Of the 20 cases with tumors, total resections were achieved in 11 cases, subtotal or large resections in 4 cases and partial resection in one case. Two patients with spontaneous rhinorrhea were successively treated surgically. 21 patients had a follow-up with a time ranging from 1-11 years (a mean of 3 years). 15 patients resumed their jobs with no evidence of recurrence of the original disease, and 5 patients able to live self-care. One patient with an olfactory neuroblastoma died 3 years after the operation owing to relapse of the tumor.

Adolescent↗
PubMed1995

[The posterolateral suboccipital approach to the lesions located at the anterior portion of the craniocervical junction].

A surgical approach to the anterior lower brainstem and upper cervical spinal cord consists of a fashion of unilateral suboccipital scalp flap, exposure and resection of the suboccipital bone and hemilamina of C1, removal of occipital condyle and the lateral mass of C1 (occasionally). The satisfaction of exposing the anterolateral portion of lower brainstem and upper cervical spinal cord can be obtained with minimal retraction of the nervous tissue. 13 patients, 9 with tumors, 2 with giant vertebral aneurysms, 2 with craniocervical malformations, underwent this operative procedure with no surgical mortality and morbidity which related to the approach.

Adult↗
PubMed1995

[Human lens epithelial cell culture and its proliferative inhibition in vitro].

The cultures of human lens epithelial cells taken from both normal and cataractous lenses were established in vitro. The biological characteristics and the histological changes of the cells were investigated. 5-Fluorouracil (5-Fu), Homoharring tonine (HH) and Harmeline (H) were used for the inhibition of the proliferative cells in the experiment. The results revealed that the in vitro survival capacity of the human lens epithelial cells is limited and the proliferative capacity of the cells is negatively correlated to the donor age. HH and H can effectively inhibit the lens epithelial cell proliferation. Based on the results of this report, performing small and smoothly edged anterior capsulorhexis in extracapsular cataract extraction may possibly decrease the incidence of the post-operative opacification of the posterior capsule.

Adolescent↗
PubMed1995

Endolymphatic stromal myosis of the uterus. Clinicopathological analysis of five cases.

Five cases of endolymphatic stromal myosis (ELSM) were studied using histological, histochemical and immunohistochemical methods. ELSM is a well-differentiated tumor resembling the normal endometrial stoma, with a low mitotic activity. So ELSM is considered as a kind of potentially malignant tumor different from endometrial stomal sarcoma and benign stromal nodules as well, though it can metastasize to the outside of uterus. ELSM may be derived from the stem cells that are normally present in the stroma of uterus, and can manifest multidifferentiation.

Adult↗
PubMed1995

[Clinical significance of fibrinolytic system defectiveness in exercise induced myocardial ischemia and its mechanism].

Plasma levels of tissue type plasminogen activator (tPA), plasminogen activator inhibitor (PAI), fibrinogen (Fg), thromboxane B2 (TXB2), 6-ketoprostaglandin F1 alpha (6-keto-PGF1 alpha), renin activity (PRA) and angiotensin II (ANGII) were assayed in 18 patients with coronary heart disease and 11 healthy subjects before and after submaximal treadmill exercise test according to "Bruce programme". All patients showed significant (> or = 50%) stenosis of at least one branch of the coronary arteries in coronary angiography and normal levels of serum trinitroglycerin. Drugs of dipyridamole, heparin, warfarin and aspirin were not administered to the patients two weeks before the test. The results were as follows: (1) Plasma PAI activity and Fg levels in 12 patients with positive test were remarkablly higher than in the remaining 6 subjects with negative test in the CHD group and in the control before and after exercise. Plasma tPA antigen changed in a reverse way. (2) Plasma levels of TXB2, PRA and ANGII in the positive test subgroup of CHD were higher than in the negative test subgroup and in the control after exercise, but differences of the parameters among the three groups were insignificant before exercise. The study suggests that defectiveness of fibrinolytic system in CHD patients was shown mainly as disorder of tPA-PAI equilibrium and that decreased fibrinolytic activity and increased PAI in exercise-induced myocardial ischemia have relations with activation of platelets and renin-angiotensin system.

Angiotensin II↗
PubMed1995

[Experimental studies on the preventive effect of artemether against schistosomal infection].

In order to study the preventive effect of artemether (Art) against schistosomal infection, mice, rabbits and dogs infected with Schistosoma japonicum cercariae were treated intragastrically (ig) with Art on various days after infection. The preventive effect was assessed by total and female worm reduction rate, the number of the animals without female worm, measurement of some parameters relevant to the acute schistosomiasis, and histopathological observation on the liver. The results showed that in mice a promising effect was obtained when an initial dose of Art 300 mg/kg was given ig on d7 after infection with cercariae, followed by repeated dosing every wk for 4 times. In rabbits and dogs treated ig with Art according to above-mentioned appropriate regimen on d7 after infection at a dosage of 10 or 15 mg/kg given every 1 or 2 wk for 2-4 times, the total and female worm reduction rates were 96.8%-100%, and part of the animals were free from female worm. After preventive treatment of the rabbits with Art, the body temperature and eosinophil count were normal and no schistosome egg was found in the feces. When rabbits infected with 48-52 schistosome cercariae once every other day for 5 times were initially treated ig with Art 15 mg/kg on d7 after the first infection, and the same dosing was given repeatedly every 1 or 2 wk for 2-4 times, the total and female worm reduction rates were 97.6%-98.4%. Histopathological observation showed that the above-mentioned infected dogs and rabbits received preventive treatment with Art exhibited a promising protective effect on their livers. The protective effect of Art given every 1 wk on the liver was similar to that of the drug given every 2 wk. The results indicate that Art possesses an effect for prevention of schistosomiasis which could be helpful for reducing infection rate and intensity of infection, and controlling acute schistosomiasis.

Animals↗
PubMed1994

Regulation of in vitro nucleic acid strand annealing activity of heterogeneous nuclear ribonucleoprotein protein A1 by reversible phosphorylation.

Phosphorylation in vivo of several proteins in the mammalian heterogeneous nuclear ribonucleoprotein complex (hnRNP), including A1, has been observed and proposed as a regulatory step in pre-mRNA splicing [Maryland, S. H., Dwen, P., & Pederson, T. (1993) Proc. Natl. Acad. Sci. U.S.A. 90, 7764-7768]. We examined the ability of recombinant hnRNP protein A1 to act as a substrate for a number of purified Ser/Thr protein kinases in vitro. A survey of seven protein kinases showed that A1 was heavily phosphorylated by protein kinase C (PKC) and also was phosphorylated by casein kinase II, protamine kinase, and protein kinase A. In contrast, autophosphorylation-activated protein kinase and two forms of myelin basic protein kinase failed to phosphorylate A1. Proteolysis with trypsin and V8 protease revealed that PKC phosphorylates A1 at three main sites, two in the N-terminal domain (spanning residues 2-196) and one in the C-terminal domain (spanning residues 197-320). Amino acid sequencing revealed that these sites were Ser95, Ser192, and Ser199; phosphorylation at Ser192 was more abundant than at Ser95 and Ser199. Phosphorylation by PKC inhibited the strand annealing activity of A1. Protein phosphatase 2A, but not protein phosphatase 1, dephosphorylated A1 and reversed the inhibitory effect of PKC phosphorylation on the strand annealing activity. A conformational change in the C-terminal domain of A1 was observed upon PKC phosphorylation, and this was associated with a decrease in A1's affinity for single-stranded polynucleotides. The results are consistent with a role of phosphorylation of A1 in regulating its strand annealing activity in vivo.

Amino Acid Sequence↗
PubMed1994

Localization of mRNA for protein phosphatase 2A in the brain of adult rats.

The gene expression for alpha and beta isoforms of type 2A protein phosphatase (PP2A-alpha and -beta) in the adult rat brain was examined by in situ hybridization analysis. No marked difference in the gene expression was discerned between the two isoforms in large portions of brain, except for the thalami in which the expression level for the alpha isoform was similar to that in the cerebral neocortex whereas that for the beta was lower than that in the neocortex. The gene expression was observed intensely in the piriform cortex, the cerebellar Purkinje and granule cell layers, and the hippocampal pyramidal and dentate granule cell layers, and the locus ceruleus, whereas the moderate levels of its expression were observed in the olfactory mitral cells and the pontine nuclei. The cerebral neocortex expressed the mRNA moderately to weakly without any laminar patterns, whereas the expression level in the caudate-putamen was very low. This expression pattern is basically similar to that of PP2C reported previously, except for the plexus choroideus and ependyma having no significant expression for PP2A.

Animals↗
PubMed1994

Determination of wrist kinematics using a magnetic tracking device.

The objective of this work is to present a method to determine the three-dimensional kinematics of the human wrist joint under physiological loading conditions using a magnetic tracking device. Euler angles were used to determine wrist extension-flexion, radial-ulnar deviation and supination-pronation. The screw displacement axis (SDA) method was used to describe the relative motion between carpal bones. Computer graphics were also used to obtain a better visualization of the three-dimensional motions of the carpal bones. This was accomplished by combining motion data and digitization data describing the geometry of the articular surfaces of the carpal bones. Geometric data included the locations of several points located on the articular surfaces forming the radio-scaphoid and radio-lunate joints. The SDA axes describing the motions of the capitate or the lunate or the scaphoid with respect to the radius during flexion-extension were found almost parallel to the medial-lateral direction. Translations along any SDA did not exceed 2 mm. One can thus consider the motion of each carpal bone as a pure rotation about a screw axis. Also, the SDA axis describing the motion of the capitate with respect to the radius was found to pass through the proximal end of the capitate. The graphical display of carpal motions shows that, as the wrist is flexed, the surface of the lunate within the radio-lunate articulation moves from palmar to dorsal. On the other hand, the palmar-dorsal location of the proximal surface of the scaphoid within the radio-scaphoid articulation remains almost unchanged.

Biomechanical Phenomena↗
PubMed1994

Lactate enhances sodium channel conductance in isolated guinea pig ventricular myocytes.

Myocardial hypoxia and ischemia result in the production of lactate. To study the effect of lactate on the rapid Na+ current (INa), we used the whole cell voltage-clamp technique in enzymatically isolated guinea pig ventricular myocytes. Experiments were conducted at 16 degrees C. Extracellular Na+ concentration ([Na+]o) was maintained in control and test solutions and extracellular pH was 7.4. Lactate (4-10 mM, either sodium lactate or lactic acid) augmented INa in each of eight experiments, increasing the peak Na+ conductance from 75.4 to 84.7 nS (13-16% at all test voltages in the linear portion of the conductance curve). The voltage dependence of steady-state availability and the time course of inactivation remained unchanged. The increase in peak Na+ conductance was concentration dependent, with an apparent dissociation constant of 1.8 mM and Hill coefficient of 1.8. Lactate in the range of 1-10 mM did not significantly reduce the Ca2+ activity of test solutions. These effects of lactate were still observed in Mg(2+)-free test solutions and when the buffering capacity of internal solution was reinforced by increasing N-2-hydroxyethylpiperazine-N'-2-ethanesulfonic acid concentration from 5 to 20 mM. In conclusion, lactate enhances INa via a mechanism that does not involve chelation of Ca2+ or Mg2+ or changes in intracellular pH. These effects of lactate on the Na+ channel might alter electrophysiological properties during myocardial ischemia and could protect the heart from ischemia-induced conduction abnormalities or, alternatively, could lead to arrhythmias.

Analysis of Variance↗
PubMed1994

Early treatment with artemether and praziquantel in rabbits repeatedly infected with Schistosoma japonicum cercariae.

When rabbits infected with 48-52 Schistosoma japonicum cercariae once every wk for 6 times or every other day for 5 times were treated ig with artemether (Art) 10 or 15 mg.kg-1 on d7 after the first infection, followed by the repeated administration of the same dose once every 1-2 wk, a promising effect was seen in the groups treated with Art at higher dose. In another group of rabbits with the same drug administration regimens of praziquantel (Pra) were also used in early treatment, but the initial dose was given on d21 after the first infection. The results showed that Pra given at 40 mg.kg-1 in each administration was more promising than the lower dose of 30 mg.kg-1 especially in group treated at 2 wk intervals. Further study indicated that the presence of adult schistosomes in rabbits increased the effect of Pra not only on 21-day-old schistosomule, but also on 14-day-old schistosomules. The results suggest that Art and Pra could be used in field trial for controlling acute schistosomiasis and decreasing the intensity of schistosomal infection.

Animals↗
PubMed1994

[Effect of artemether on glycogen, protein, alkaline phosphatase and acid phosphatase of Schistosoma japonicum].

When mice infected with Schistosoma japonicum for 32-35 d were treated ig with artemether (Art) at a single dose of 300 mg.kg-1 for 24 h, the glycogen content of female and male schistosomes decreased significantly with reduction rates of about 50%. 72 h after medication, the glycogen reduction rates were 64.1-77.9%. Meantime, the protein content of female and male worms was also decreased, the reduction rates being 68.1% and 49.3%, respectively. In infected mice treated ig with Art at the same dosage for 24 h, the inhibition rates of alkaline phosphatase (AKP) activity in female and male worms were 30% and 25%, respectively. 72 h later, the AKP activity of female worm was further inhibited to 62.3% as compared with the control. Besides, the inhibitory effect of Art on acid phosphatase (ACP) activity of female worm was also more apparent than that of male worm. 72 h after medication, the respective inhibition rates of ACP activity in female and male worms were 75.7% and 47.6%. The results indicated that Art might exert its effect on both carbohydrate and protein metabolism of schistosomes.

Acid Phosphatase↗
PubMed1994

The biological study of the cultured human lens epithelial cells in vitro.

The human lens epithelial cells (HLE) cultured in vitro was established in normal and cataractous lenses. The biological feature, histological characteristics and the ultrastructure of the cultured HLE cells were investigated. The results reveal that the proliferative capacity of the cultured HLE cells is reversely proportional to the donor age; the cultured HLE cells has the limited proliferative capacity in vitro. The relieve of the contact inhibition is the effective trigger of the HLE cell proliferation. This research work is possible to make a basis for the further study of the regeneration of the lens and the roles of the lens epithelial cells in the development of the cataract.

Adolescent↗
PubMed1994

Maternal and fetal brain and plasma levels of cocaine and benzoylecgonine after acute or chronic maternal intravenous administration of cocaine.

The effect of repeated i.v. administration of cocaine HCl (1.5, 3 or 6 mg/kg daily) from gestational day 8 through gestational day 18 was studied on maternal and litter parameters in the pregnant female Sprague-Dawley rat. These doses of cocaine had no significant effect on maternal weight gain or nutritional intake and did not significantly affect litter size. Levels of cocaine and its metabolite benzoylecgonine in the brain and plasma of the dams and their fetuses were measured on gestational day 18 at 1, 5, 20 or 60 min after a single injection or 11 daily i.v. injections of cocaine (6 mg/kg). The shape of the time courses for cocaine differed somewhat between dams and fetuses, with fetal plasma concentrations of cocaine initially being lower than those of their dams and then by 5 min becoming equivalent to those of their dams. Although plasma concentrations of cocaine soon equilibrated between dams and fetuses, plasma concentrations of benzoylecgonine did not. Interestingly, brain concentrations of cocaine did not differ between dams and fetuses. The most remarkable finding was that the relative distribution of cocaine between brain and plasma differed after chronic vs. acute treatment, with a relative shift in the distribution of cocaine from plasma to the brain in the fetuses, and with the exception of the earliest time point measured, in the dams after repeated dosing.

Animals↗
PubMed1994

[Studies on natural foci of tsutsugamushi disease of the autumn-winter type in Jiangsu].

Before 1986, tsutsugamushi disease was known only prevalent in south to Zhejiang Province in our country, belonged to the summer type and Leptotrombidium (L.) deliense was regarded as the main vector. In October 1986, the authors found this disease in Nanjing and carried out a series of studies in 1986-1992. The results were as follows: Tsutsugamushi disease was epidemic in Nanjing and north of Jiangsu (including: Dongtai, Haian, Rudong, Jinhu, Hanjiang, Jiangdu); belonged to the autumn-winter type; the main reservoir hosts were Apodemus agrarius, Rattus confucianus, R. norvegicus and Crocidura lasiura; the transmitting vector was L. (L.) scutellare; the pathogen of tsutsugamushi disease of the autumn-winter type-Rickettsia tsutsugamushi belonged to low-virulent strain, and could not easily be detected; after the inoculated mice were treated with diluted cyclophosphamide solution, 14 strains of R. tsutsugamushi have been isolated from rats, mites and patients; serological typing of their sera showed that they belonged to the Gilliam type; natural foci in Jiangsu could be divided into two types--flat land and hilly land.

Animals↗