Search PubMed⌕ Search

Biomedical subjects

G Ma

Publications and source records attributed to G Ma.

At least 91 records · Page 5Linked to original sources
PubMed1995

Molecular characterization and identification of Saprolegnia by restriction analysis of genes coding for ribosomal RNA.

Restriction fragment length polymorphisms (RFLPs) in two regions of the ribosomal DNA (rDNA) repeat unit were examined in 33 strains representing 18 species of Saprolegnia. The Polymerase Chain Reaction (PCR) was used to separately amplify the 18S rDNA and the region spanning the two internal transcribed spacers (ITS) and the 5.8S ribosomal RNA gene. Amplified products were subjected to a battery of restriction endonucleases to generate various fingerprints. The internal transcribed spacer region exhibited more variability than the 18S rDNA and yielded distinctive profiles for most of the species examined. Most of the species showing 100% similarity for the 18S rDNA could be distinguished by 5.8S + ITS restriction polymorphisms except for S. hypogyna, S. delica, S. lapponica, and S. mixta. The rDNA data indicate that S. lapponica and S. lapponica and S. mixta are conspecific with S. ferax, whereas there is no support for the proposed synonymies of S. diclina with S. delica and of S. mixta with S. monoica. Results from cluster analysis of the two data sets were very consistent and tree topologies were the same, regardless of the clustering method used. A further examination of multiple strains in the S. diclina-S. parasitica complex showed that restriction profiles are conserved across different strains of S. parasitica originating from the U.K. and Japan. HhaI and BsaI restriction polymorphisms were observed in isolates from the U.S. and India. The endonuclease BstUI was diagnostic for S. parasitica, generating identical fingerprints for all stains regardless of host and geographic origin. Except for the atypical strain ATCC 36144, restriction patterns were also largely conserved in S. diclina. Correlation of the rDNA data with morphological and ultrastructural features showed that S. diclina and S. parasitica are not conspecific. Restriction polymorphisms in PCR-amplified rDNA provide a molecular basis for the classification of Saprolegnia and will be useful for the identification of strains that fail to produce antheridia and oogonia.

Base Sequence↗
PubMed1995

An experimental study of intravascular stent in abdominal aorta of atherosclerotic miniature pigs.

To study the effects of nitinol alloy stent in the treatment of atherosclerotic arterial stenosis, eight miniature pigs were subject to abdominal aortic balloon denudation and high-fatty food. Then 8 nitinol alloy stents were implanted into each abdominal aortas of pigs. The pigs were equally divided into two groups. One group was given captopril (3 mg/kg/d). All animals were sacrified for pathological examination 6 to 10 months after stent implantation. The degree of arterial intima proliferation in the areas of stent implantation not significantly different from that of areas of balloon denudation alone; the atherosclerotic lesions were found at the arterial surface of stent implantation sites. The intima layer was rich in smooth muscle cells, with atherosclerotic plaque formed around the stent wire. On the other hand, significant decrease in arterial intima proliferation was found in group II with no atherosclerotic plaque. The arterial stenosis resulting from atherosclerotic lesion could not be prevented by implantation of intravascular stent, and on the contrary, the mechanical stress of stent wire might worsen the atherosclerosis. Captopril might impede the development of atherosclerotic stenosis after stent implantation.

Alloys↗
PubMed1995

[Repair of large cranial defect using allogeneic cranial bone and bone morphogenetic protein].

We have successfully treated 4 patients with large cranial defects using a composite of allogeneic cranial bone, BMP (bone morphogenetic protein), pedicled periosteum and skin flap. The size of the cranial defects ranged from 9 cm x 7 cm to 13 cm x 11.5 cm. One to two years' follow-up showed that the wounds in all patients healed primarily with good appearance. The allogeneic bone graft was absorbed and substituted by new bone formation.

Adult↗
PubMed1995

Asymptotic confidence bands for generalized nonlinear regression models.

Asymptotic confidence bands for generalized nonlinear regression models are developed. These are based on a combination of the S method of Scheffe, together with the delta method which is used to approximate the mean function by a linear combination of the parameters. The approach can be used in any situation where large sample theory can be applied to yield asymptotically normal estimates of the parameters, together with a consistent estimate of the large sample covariance matrix. Alternative formulations for various special cases allow the use of restricted range bands. A number of examples are given, including a pharmacokinetic model, a logit model with a background response rate, and a parametric survival model.

Administration, Inhalation↗
PubMed1995

[Shape memory angioembolus for varicocele].

Seven target veins (in 5 dogs) were embolized with nitinol conical rugby embolus (NT-CRE). The pathological examination showed firm impact between NT-CRE and intravenous membrane without misembolization from retrograde flow. Compact collagenous fibrous tissue was seen in and out NT-CRE on spaces. On the basis of animal experiment, 10 patients with varicocele were treated with NT-CRE. After the operation, the varicocele and symptoms disappeared and venae spermatica collapsed. The follow-up for 1.5-2.3 years showed no recurrence in the 10 patients. We consider that the therapeutic method is simple and effective for varicocele.

Adolescent↗
PubMed1995

[Effects of SL-probiotic preparation on the body weight and phagocytosis of white mice].

Effects of SL-probiotic preparation on the body weight and the phagocytic functions in white mice were studied. Bioassay of its toxicity showed SL-P was non-toxic. Body weight of the treated mice increased significantly as compared with that of controls 10 days after treatment with SL-probiotic preparation. Phagocytic activity, acid phosphatase activity, lysozyme activity of the peritoneal macrophages of the tested mice were enhanced significantly as compared with those of normal controls. The same results were obtained with respect to serum lysozyme activity. These observations showed that SL-probiotic preparation could activate macrophage function in mice and hence enhancement of non-specific immunity.

Acid Phosphatase↗
PubMed1994

7 beta-hydroperoxycholest-5-en-3 beta-ol, a component of human atherosclerotic lesions, is the primary cytotoxin of oxidized human low density lipoprotein.

Modification of low density lipoprotein (LDL) by free radical oxidation renders this molecular complex cytotoxic. Oxidized lipoproteins exist in vivo in atherosclerotic lesions and in the plasma of diabetic animals, suggesting that lipoprotein-induced tissue damage may occur in certain diseases. We undertook purification and identification of the major cytotoxin in oxidized LDL. The lipid extract from oxidized LDL was subjected to multiple HPLC separations, and the fractions were assayed for cytotoxicity. Mass spectrometry and nuclear magnetic resonance identified the purified toxin as 7 beta-hydroperoxycholest-5-en-3 beta-ol (7 beta-OOH-Chol). This molecule accounted for approximately 90% of the cytotoxicity of the lipids of oxidized LDL. We also found 7 beta-OOH-Chol in human atherosclerotic lesions from endarterectomy specimens obtained immediately after excision. These results are consistent with the hypothesis that the oxidized LDL present in lesions has the capacity to induce cell and tissue injury, leading to progression of the disease and the generation of the necrotic core of the lesion.

Arteriosclerosis↗
PubMed1994

[Comparative effects of calcium channel blockers and L-arginine on chronic intermittent hypoxic pulmonary hypertension in rats].

Experiments were carried on rats to study the preventive effects of calcium channel blockers Nitrendipine, Nifedipine and L-Arginine (L- Arginine is the physiological precursor of nitric oxide in endothelium-dependent relaxation) on chronic intermittent hypoxia induced pulmonary hypertension, on the right ventricular hypertrophy and pulmonary vascular pathologic changes. The results showed (1) Nitrendipine, Nifedipine and L-arginine played significant role in preventing chronic hypoxic pulmonary hypertension and the right ventricular hypertrophy. (2) There was no significant difference between Nitrendipine, Nifedipine and L- arginine in preventing hypoxic pulmonary hypertension (P > 0.05). (3) Nitrendipine was better than Nifedipine in reducing the hypoxic pulmonary hypertension.

Animals↗
PubMed1993

The development of sleep-wakefulness rhythm in normal infants and young children.

The development of circadian sleep-wakefulness rhythm was investigated by a longitudinal study of two normal newborns for two and a half years and by a transversal study of 182 normal infants and young children living in three different areas of Japan. The circadian rhythm became established before 4 months of age, and daytime sleep became concentrated within two time periods from 7 months of age, and then within a single peak from 14 months of age. The time period 00:00-04:00 developed into the "absolute sleep period" from 3 months of age, and the "absolute wakefulness period" appeared first in the time period 08:00-11:00 from 14 months of age, and then in the time period 16:00-21:00 from one and a half years of age. Establishment of circadian rhythm as indicated by the numbers of sleep epochs in daytime and in nighttime, and the longest continuous sleep or wakefulness periods reflect the development of the nervous system and were influenced by the change of light-dark in the environment. These parameters showed critical ages, but not sexual or regional differences. However, regional differences were found in the times of waking up in morning and falling asleep at night. This indicated the phase of the circadian rhythm was also influenced by natural and social environmental factors.

Aging↗
PubMed1993

Jejunal diverticulosis.

Jejunal diverticulosis is considered to be a generally asymptomatic condition in which the diverticula are pulsion mucosal herniations with walls lacking a muscle layer. These opinions in particular are examined in this review of 20 cases of jejunal diverticulosis treated during an 8 year period. The predominant complication in each case was inflammation or perforation (nine), diarrhoea or malabsorption (five), haemorrhage (three), chronic abdominal pain (two) and pseudo-obstruction (one). At least 10 patients had more than one complication, although this was often unrecognized. Ten patients complained of chronic abdominal pain, in eight of whom the cause was not diagnosed until other complications supervened. Unrecognized malabsorption may be common, as the mean serum albumin in 12 patients presenting acutely with inflammation, perforation or haemorrhage, was low (mean 32 g/L, normal 39-48 g/L). Histology sections were reviewed in the 12 cases that underwent resection, of whom 11 were suitable for classification. Four cases had narrow-mouthed pulsion diverticula with a thin or absent muscle coat, and had developed at the point of blood vessel penetration. Four cases had wide-mouthed diverticula in which the muscle layer was present, suggesting an abnormality of the intestinal wall. Two had features of both. In one case a Meckel's type diverticulum was located 10 cm from the duodenal-jejunal flexure. Seven had mucosal villous atrophy consistent with bacterial overgrowth. In conclusion, jejunal diverticulosis may be associated with complications more frequently than has been recognized and pathologically is a diverse condition.

Aged↗
PubMed1992

[Preliminary studies of the relationship between micronucleus formation and cell cycle. IV. Micronucleus formation induced by chemical mutagens at G0, G1, S and G2 phases of human lymphocytes].

In this paper the authors studied quantitatively the micronucleus formation at various phases of interphase in human lymphocytes induced by chemical mutagens by means of control of cell culture intervals, autoradiography and block of metaphase cells etc. The results show that mutagenic anti-tumor drugs: bimolane (treatment in vitro) and thio-tepa etc. (treatment in vivo) can induce micronucleus formation at various phases of interphase in lymphocytes. The frequency of micronucleus (MNF) induced at G1 phase is significantly higher than that at G0 and G2 phase. The MNF at S phase of cells is obviously lower than at G1. This result suggests that most of the micronucleated cells at G1 phase do not enter S phase and micronucleus rarely form at S phase of cells.

Adolescent↗
PubMed1990

[Hemodynamic effects of renal interoreceptor and afferent nerve stimulation in rabbit].

Hemodynamic effects of renal mechano- and chemoreceptor activation and afferent renal nerve stimulation were observed in 39 anesthetized rabbits. The mean arterial pressure (MAP) and heart rate (HR) were decreased following elevation of ureteral pressure (13-22 mmHg), and retrograde perfusion of NaCl (1.0 mol/L) or KCl (0.15 mol/L) into pelvis via ureter route. The decrease in MAP was enhanced by sinoaortic denervation. HR, MAP, mesentery arterial perfusion pressure (MPP), hindlimb arterial perfusion pressure (HLPP), left ventricular pressure (LVP), left ventricular dp/dtmax (LV dp/dtmax), cardiac output (CO) and total peripheral resistance (TPR) were decreased during electrical stimulation of afferent renal nerve. By sinoaortic denervation, the aforementioned hemodynamic parameters, except HR, CO and TPR, were reduced more markedly by electric stimulation of afferent renal nerves. Therefore it appears that sinoaortic depressor reflex plays a buffer role in the cardiovascular responses to the stimulation of afferent renal nerves.

Afferent Pathways↗
PubMed1990

[Observation on the afferent nerve activity induced by stimulation of renal receptors in the rabbits].

The effects of stimulation of renal mechano- and chemoreceptors on the afferent renal nerve activity (ARNA) were observed in 44 anesthetized rabbits. The results obtained were as follows: (1) Elevation of ureteral pressure (UP) could induce an increase in integral value of ARNA by 175.13 +/- 22.41% (P less than 0.001). (2) KCl (0.15 mol/L) and NaCl (1 mol/L) perfused retrogradely into pelvis via ureter route resulted in increase of integral value of ARNA by 253.79 +/- 21.64% and 172.17 +/- 15.19% (P less than 0.001), respectively. (3) Four patterns of afferent unit discharge were found: no spontaneous activity, regular spontaneous activity, regular spontaneous activity with burst and irregular spontaneous activity. (4) The units of afferent renal nerve with no spontaneous activity were activated markedly by elevation of UP, while the units with spontaneous activity showed no change. (5) In response to the retrograde perfusion of KCl (0.15 mol/L) and NaCl (1 mol/L) into pelvis, the activity in units with spontaneous discharge increased markedly by 210.70 +/- 23.40% and 140.07 +/- 15.72% (P less than 0.001), respectively, and the other units may be recruited concomitantly. (6) The units with no spontaneous discharge were activated by renal artery occlusion. The results implied that there are mechanoreceptor, R1 and R2 chemoreceptors in the kidney of the rabbit, and they may sense the change in UP, renal ischemia and ionic (K+, Na+) concentration of the solute within pelvis.

Action Potentials↗
PubMed1988

Development of a tooth germ within an autogenous clavicular graft.

The left side of the mandible distal to the second primary molar of a 3 years old Southern Chinese boy was resected as a result of osteomyelitis. A diaphyseal clavicular graft pedicled on the sternomastoid muscle was selected for the reconstruction of the mandible. By the age of 6 years, the mandible although stunted in size did exhibit appropriate remodelling. In addition a tooth germ in the region of the second permanent molar was found developing in the autogenous bone graft of the mandible.

Bone Transplantation↗