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Biomedical subjects

P Ma

Publications and source records attributed to P Ma.

At least 55 records · Page 3Linked to original sources
PubMed1996

Discriminating and continuous measurement of photosynthesis and respiration by monitoring 13CO2 and 12CO2 as tracers.

The simultaneous and discriminative measurement of the photosynthesis and the respiration of the plant was attained by simultaneous monitoring of 13CO2 and 12CO2 by artificial control of 13CO2 abundance of ambient air. The principle of the measurement is based on the following physiological processes. 6CO2 + 12H2O --> C6H12O6 + 6O2 + 6H2O, 6(13C)O2 + 12H2O --> (13C6)H12O6 + 6O2 + 6H2O, 6CO2 + 12H2(18O) --> C6H12O6 + 6(18O)18O + 6H20. Assuming that respiratory consumption of the new born carbon substrate fixed by photosynthesis is negligible during the measurement, the photosynthetic CO2 consumption VPCO2 and the respiratory CO2 production VRCO2 are measured according to the estimation (1) or (2), (1) for closed method, VPCO2 = k(V0 - V t)¿ F13CO2 + (F12CO2/F13CO2)F13CO2 ¿, VRCO2 = k(V0 - V t)¿ F12CO2 - (F12CO2/F13CO2)F13CO2 ¿, (2) for open method, VPCO2 = kVE ¿ (FI13CO2 - FE13CO2) + (F12CO2/F13CO2)(FI13CO2 - FE13CO2) ¿, VRCO2 = kVE ¿ (FI12CO2 - FE12CO2) - (F12CO2/F13CO2)(FI13CO2 - FE13CO2) ¿ where V0 is initial volume of growth chamber including attached flexible bag, FICO2 is the inlet or initial gas concentration of CO2 and FECO2 is the ambient gas concentration of CO2 in the chamber, V and VE are the sampling rate of mass spectrometer and the ventilation rate of the growth chamber respectively, k is the STPD conversion factor = ¿273(PB-PH2O)/760(273+tE)¿, tE(degrees C) is the ambient gas temperature. In the closed method, the gas container of the growth chamber is circulated, resulting FECO2 is varied according to the balance of consumption and production of CO2, while in the open method VE is controlled to keep FECO2 at a constant value. Both (1) and (2) methods were examined and evaluated on the measurements of komatsuna and maize.

Argon↗
PubMed1996

[Level and significance of the soluble interleukin-2 receptor expression in serum of patients with bladder cancer].

The results of a dynamic study of the soluble interleukin-2 receptor (SIL-2R) expression, interleukin-2 (IL-2) production and natural killer cell factor (NKCF) activity before and after operation in 24 bladder carcinoma patients were reported. The SIL-2R expression level in the patients was significantly higher, the IL-2 production and NKCF activity were remarkably lower than those of controls. Furthermore, the higher the stage of the tumor, the higher the level of the SIL-2R. There was a period of immune suppression after operation. The results suggest that the changes of the SIL-2R expression level, IL-2 production and NKCF activity are closely related to the prognosis of patients with bladder carcinoma.

Aged↗
PubMed1995

Effects of glucose-dependent insulinotropic polypeptide and glucagon-like peptide-I-(7-36) on insulin secretion.

Glucose-dependent insulinotropic polypeptide (GIP) and glucagon-like peptide (GLP)-I-(7-36) are probably the most important "incretins," but there is controversy as to their relative insulinotropic activities. The effects of natural (np) and synthetic porcine (sp) GIP, synthetic human (sh) GIP, and GLP-I-(7-36) on insulin secretion from the perfused rat pancreas were compared using gradient perfusion. Insulin secretion was increased by both spGIP and GLP-I-(7-36) at concentrations of approximately 16 pM. Maximal responses to GLP-I-(7-36) in the presence of 16.7 mM glucose were slightly greater than with npGIP or spGIP, but with 10 mM glucose spGIP and GLP-I-(7-36) exerted equivalent effects. Responses to shGIP were greatly reduced compared with spGIP. In the presence of 50 pM spGIP or GLP-I-(7-36) the glucose threshold was 4.5 +/- 0.11 mM. The data indicate that GLP-I-(7-36) and porcine GIP are equally insulinotropic and share the same glucose threshold for activity, whereas shGIP is less active. At the concentrations found postprandially, however, GIP is likely to be the more important incretin.

Animals↗
PubMed1995

[Fine stereo structure for natural organic molecules, a preliminary study. II. Melting point influenced by structure factors].

Crystal structures of two compounds from Tripterygium wilfordii Hook f. have been determined by X-ray diffraction method. Structure factors influencing melting point of solid state have been analysed. Crystal class (or space group), recrystallization solvent, force between molecules and fine changes of molecular structures will all cause melting point changes of crystal substance.

Crystallography, X-Ray↗
PubMed1993

Management of major arterial injuries of the limbs in 166 cases.

The charts of 166 patients with major arterial injuries (175 arterial repairs) inflicted during periods of peace and war time were reviewed. One hundred and sixty-seven (95%) of the arteries repaired remained patent. Nine patients had limbs which developed ischemic contracture. Nine patients required amputations. Follow-up data was obtained from seventy-five patients with an average follow-up of five years and one month (six months to thirty years). Early diagnosis, prompt treatment including fasciotomies when indicated, complete debridement, appropriate coverage, meticulous surgical technique, and simultaneous treatment of concomitant injuries are all crucial factors in successful limb salvage. Major arterial injuries of the limb occur frequently in our patient population, especially in time of war. Successful treatment of major arterial injuries may be life-saving, as well as allowing limb salvage and restoration of limb function. The purpose of this study is to review our experience with repair of major arterial injuries.

Adolescent↗
PubMed1993

Pharmacology of 2-amino-1,4-dihydro-4-(2-[4-[4-(2-methoxyphenyl)-1- piperazinyl]butylsulfinyl]phenyl)-6-methyl-5-nitro-3-pyridine carboxylic acid methyl ester (XB513), a novel calcium agonist with alpha-1 adrenergic receptor antagonistic.

2-Amino-1,4-dihydro-4-(2-[-4[4-(2-methoxyphenyl)-1-piperazinyl]- butylsulfinyl]phenyl)-6-methyl-5-nitro-3-pyridine carboxylic acid methyl ester (XB513) was designed to combine the calcium agonistic and alpha-1 adrenergic receptor antagonistic properties in the same molecule. It inhibited the specific binding of [3H] nitrendipine in rat cardiac ventricular membranes with an IC50 of 1.2 microM, which is 20-fold greater than the standard calcium agonist Bay K 8644. It displaced [3H]prazosin in rat brain membranes with an IC50 of 29 nM. XB513 caused concentration-dependent positive inotropic responses in isolated electrically paced guinea pig left atria with an EC50 of 1.2 microM and was 10 times less potent than Bay K 8644. In rabbit aorta, XB513 inhibited the contractile effect of 16 nM norepinephrine with an IC50 of 89 nM. In an acute heart failure dog model produced by an overdose of propranolol, XB513 at 0.3 to 3 mg/kg i.v. dose-dependently reversed the decreased mean arterial pressure, cardiac output and dP/dt as well as the increased left ventricular end diastolic pressure induced by propranolol. In conscious instrumented dogs, XB513 at 0.1 and 0.3 mg/kg i.v. increased dP/dt and heart rate significantly, with a minor effect on mean arterial pressure. In summary, this study demonstrates that XB513 is a novel chemical entity possessing both calcium agonistic and alpha-1 adrenergic receptor blocking properties and thus may represent a new class of agents for the treatment of congestive heart failure.

Adrenergic alpha-Antagonists↗
PubMed1992

Prognostic factors in assessment and management of male infertility.

Evaluation of 304 infertile couples with at least one abnormal semen analysis (sperm density < 20 x 10(6)/ml and/or motility < 50%) and no apparent female factors was performed in a multicentre prospective cohort study. In 73 cases therapeutic donor insemination was performed (TDI group) with a resulting pregnancy rate of 48%. The remaining 231 couples (non-TDI group) had an overall pregnancy rate of 25%. The TDI group had a shorter duration of infertility. The ages of both partners were comparable in TDI and non-TDI groups. In the non-TDI group, univariate analysis resulted in identification of six clinical variables associated with a change in pregnancy rates. The strongest association was noted for length of infertility. There was a weaker association for semen volume, concentration of leukocytes in semen, history of pregnancy in the female partner and laparoscopy. Multiple variable analysis of data from the non-TDI group revealed that independent predictors of pregnancy were 'duration of infertility' and 'history of pregnancy in the female partner'. The multiple variable modelling suggested that (i) an increase in the length of infertility by 1 month prolongs the time to pregnancy by an additional 1.6% (95% confidence interval: 1.5-1.7%); and (ii) a history of past pregnancy in the female partner reduces the time of pregnancy by 51% (95% confidence interval: 47-56%).

Female↗
PubMed1992

[Studies on the determination of plasma level and pharmacokinetic parameters of anisodamine by micellar liquid chromatography].

Anisodamine is a tropane alkaloid isolated from the plant Anisodus tanguticus (Maxim) Pasch. It is an anticholine drug widely used in clinics. Micellar liquid chromatography is a new type of HPLC developed in the 1980's. Direct plasma injection technique is the application of micellar HPLC in bioanalyses. In this paper, a micellar HPLC method, which employs n-propanol as modifier, SDS as surfactant, atropine sulphate as internal standard, has been developed. By direct injection, this method was successfully applied to the measurement of plasma level of anisodamine. Application of this method to the study of anisodamine pharmacokinetics was investigated in human volunteers following a single intramuscular injection. The separation was performed in a Shim-pack CLC-CN column (150 mm x 6 mm ID, 5 microns) with a mobile phase of n-propanol-water (15:85) with 45 mmol/L SDS and total ion strength 70 mmol/L by adding phosphate, and detected at 205 nm. The standard curve was linear over the concentration range of 15-750 ng plasma level (r = 0.9972). The measurable lowest concentration was 10 ng/ml plasma (S/N = 3:1). The study of anisodamine pharmacokinetic in man was also described.

Adolescent↗
PubMed1992

[Determination of bendazac lysine by RP-HPLC].

Bendazac (BD) was separated on a CLC-ODS column, 150 x 6 mm id (Shimadzu), using methanol acetic acid 0.1 mol/L (67:33) as the mobile phase. The flow rate was 1.0 ml/min and the detection wavelength, 254 nm. The detection limit of BD was 0.1 ng (R/N, 3:1), which was determined by the peak area measurement using an external standard method. The calibration curve was linear in the range of 5-10 micrograms (r = 0. 9998). The average recovery of BDL was 99.46 +/- 0.59% (n = 9). This method has been applied satisfactorily to the determination of BDL samples.

Chromatography, High Pressure Liquid↗
PubMed1990

Comparison of an indirect fluorescent antibody test and stool examination for the diagnosis of cryptosporidiosis.

A total of 342 patients, 70 with AIDS and 272 without AIDS, who had gastro-intestinal illness were selected for tests for cryptosporidiosis. Stool and serum specimens were obtained from each patient. The stool specimens were examined for cryptosporidial oocysts by acid-fast stain and the serum specimens were tested for specific antibodies against oocysts by an indirect fluorescent antibody (IFA) test. The oocysts were detected in stool specimens of 68 patients (19.8%), whereas specific antibodies were demonstrated in 102 patients (29.8%). The incidence of cryptosporidiosis was 47.1% in AIDS and 12.9% in non-AIDS patients as shown by stool examination, compared to 50% and 24.6% as shown by the IFA test. Based upon the finding of oocysts in stool specimens, the sensitivity and specificity of the IFA test in the diagnosis of cryptosporidiosis was 92.6% and 85.8%, respectively.

Acquired Immunodeficiency Syndrome↗
PubMed1990

Treatment with bovine hyperimmune colostrum of cryptosporidial diarrhea in AIDS patients.

Cryptosporidium parvum may cause severe, debilitating diarrhea in patients with AIDS. Recent anecdotal reports have suggested that hyperimmune bovine colostrum may be effective. We conducted a double-blind, controlled pilot study of hyperimmune bovine colostrum for diarrhea due to cryptosporidiosis in five AIDS patients. The patients were randomized to receive either hyperimmune or control colostrum by continuous nasogastric infusion for 10 days. All stools were collected, graded, and weighed, and the concentration of oocysts excreted was determined daily. One of the three patients treated with hyperimmune colostrum had a reduction in diarrhea and in the concentration of oocysts excreted. A second treated patient had a modest decrease in the concentration of oocysts excreted. Two patients who received control colostrum also had decreases in the volume of diarrhea but no change in the concentration of oocysts excreted. We conclude that hyperimmune colostrum with high titers of specific anti-Cryptosporidium antibody could be effective in treating patients with cryptosporidiosis. However, more studies of cow colostral immunoglobulin need to be performed so that the efficacy of this treatment can be assessed more thoroughly.

Acquired Immunodeficiency Syndrome↗
PubMed1990

Cryptosporidiosis in AIDS and non-AIDS patients.

Stool specimens were collected from 433 diarrheal patients (87 AIDS and 346 non-AIDS), among which, 154 specimens from 84 patients (45 AIDS and 39 non-AIDS) had cryptosporidial oocysts detected by acid-fast stain method. The overall incidence of cryptosporidiosis in this study was 19%; however, the incidence in the AIDS patients was almost 5 times of that in the non-AIDS patients. The consistency of 154 specimens having oocysts were 71 (46%) watery, 57 (37%) loose and 26 (17%) soft. The consistency of positive specimens from the AIDS patients and the non-AIDS patients were different; among 86 from AIDS patients, 54 (63%) of them were watery and 7 (8%) were soft; whereas in 68 positive specimens from the non-AIDS patients, 32 (47%) were loose and 19 (28%) were soft. The positive cases were found all-year-round and with a slightly higher incidence in December-February, 30 cases (36%), and in June-August, 23 cases (27%). Although a few enteric bacteria pathogens and protozoan parasites were also found in the stool specimens of patients with cryptosporidiosis, no close association with Cryptosporidium was found. As shown in this study, cryptosporidiosis is the leading cause of gastro-intestinal illness in great New York area and is not uncommonly found in AIDS and non-AIDS patients.

Acquired Immunodeficiency Syndrome↗