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Biomedical subjects

M G Chen

Publications and source records attributed to M G Chen.

At least 55 records · Page 3Linked to original sources
PubMed1991

Fasciola hepatica infection in China.

Fasciola hepatica is one of the most common parasites in China that infects ruminants, especially cattle, sheep and goats, and causes considerable morbidity and economic losses in the animal husbandry. The climate in wide areas of China is suitable for the development of F. hepatica and its intermediate snail hosts. However, human infection with the fluke is not common. Up to now, 38 hospital patients and six infected individuals from two epidemiological surveys have been reported in the Chinese literature. F. gigantica infection in herbivorous animals is comparatively rare compared to F. hepatica infections, and only one case was reported in man (Wang, 1984). This paper reviews mainly human infections with F. hepatica in the Chinese literature. Animal infections of the parasite are also briefly described.

Animals↗
PubMed1989

Progress and problems in schistosomiasis control in China.

In China, schistosomiasis control has been given a high priority in public health for more than 30 years. Among 372 counties formerly endemic for S. japonicum, transmission has been interrupted in 125 counties and in 141 counties it is under effective control. The numbers of infected persons and infected cattle were estimated to be 10 million and 1.2 million respectively in the 1950s compared with recent estimates of 870,000 (1987) and 100,000 (1986) respectively. Oncomelania snail habitats were reduced from more than 14 billion square metres in 1950s to 3.2 billion square metres in 1987. However, the endemic areas left, mainly in lake and mountainous regions, present greater difficulties and to bring them under control is a long-term task.

Animals↗
PubMed1987

Light scatter and cell surface properties of murine megakaryocyte progenitor cells.

The characteristics with respect to light scatter and cell surface properties of megakaryocyte colony-forming cells (CFU-Meg), growing in serum-free agar cultures, have been determined. Mouse bone marrow cells were fractionated using a light-activated cell sorter (FACS) either on the basis of light scatter or after staining with a fluorescein isothiocyanate (FITC)-labeled lectin or monoclonal antibody. After staining and sorting, the recovery of CFU-Meg was about 50%. In the unsorted controls 29 +/- 2 CFU-Meg/10(5) cells were observed. The forward (FLS) and perpendicular (PLS) light scatter intensities of CFU-Meg were very similar to those of spleen colony-forming cells (CFU-S) and early progenitor cells. The average diameter of the CFU-Meg as determined by the FLS intensity profile was about 7.5 microns. Wheat germ agglutinin binding of CFU-Meg was high, indicating a high sialic acid content of the cell surface. Expression of the differentiation antigen Pgp-1 on the CFU-Meg as determined by indirect immunofluorescence with the rat monoclonal antibody I42/5.1 was moderate. Pgp-1 expression was lower than the Pgp-1 expression of granulocyte/macrophage progenitors (CFU-C) or granulocytes. It is concluded that the light scatter and cell surface properties of CFU-Meg are similar to those of CFU-S and early committed progenitors.

Animals↗
PubMed1986

Effects of Pseudomonas aeruginosa on bronchial epithelial ion transport.

During chronic lung infections the effects of bacterial exoproducts on the function of the airways epithelium could play a role in the overall pathophysiology of infection. We measured the effects of Pseudomonas aeruginosa culture on ion transport and solute permeability of dog bronchial epithelium to determine if this organism produces toxins that affect these epithelial functions. Thirty-six-hour trypticase soy broth cultures of P. aeruginosa at 1:40 dilutions decreased short-circuit current and active sodium absorption and lowered conductance and chloride unidirectional fluxes. At 1:4 dilutions, P. aeruginosa increased conductance and the permeability coefficient of 14C-mannitol, suggesting that solute flow around cells was increased. These effects appear to be caused by a heat-stable glycolipid hemolysin produced by P. aeruginosa.

Animals↗
PubMed1986

In vivo and in vitro modulation of megakaryocytopoiesis and stromal colony formation by lithium.

The ability of lithium to influence in vivo and in vitro megakaryocytopoiesis and the hematopoietic microenvironment from marrow and splenic tissues was investigated. For three consecutive days, mice were injected intraperitoneally with ultrapure lithium chloride (1.6 mg/kg body weight). Animals were killed on days 1 through 4 and thereafter on alternating days until day 16. Megakaryocytopoiesis was evaluated by culturing marrow and splenic cells for their megakaryocyte stem cell (CFU-M) content. The marrow and splenic microenvironment was determined by measuring stromal colonies. Increases in marrow CFU-M were noted on the first 3 days after Li, with the maximum effect on day 2 (180% of control). A second wave of megakaryocytopoiesis began on day 6 and peaked on day 10 (165% of control). Splenic megakaryocytopoiesis was also stimulated by Li; maximum production occurred on day 10 (330% of control). Splenic stromal colony formation was elevated on the 12 days after Li. Numbers of marrow stromal colonies were elevated on days 6, 10, and 12. The increased numbers of marrow- and splenic-derived CFU-M elevated the level of circulating platelets for 10 days after Li. Dose-response Li (0.01 to 10 mmol/L) studies performed in vitro demonstrate that Li effectively increased the number of both CFU-M and stromal colony-forming cells in the presence of optimal concentrations of conditioned media used to stimulate the formation of CFU-M. Furthermore, when stromal colonies were used as feeder layers overlaid with normal nonadherent marrow cells, Li-stimulated stromal colonies supported a greater number of CFU-Ms than did normal, non-Li-treated stromal cultures.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1985

Lithium-stimulated recovery of granulopoiesis after sublethal irradiation is not mediated via increased levels of colony stimulating factor (CSF).

We have previously demonstrated that lithium (Li) is an effective agent in accelerating the recovery of granulopoiesis following sublethal (2 Gy) whole body irradiation. In this report, studies are described that further define this Li-mediated recovery by measuring the levels of colony-stimulating factor (CSF) present in serum from mice administered 105 micrograms/mouse (total dose) of ultra-pure Li2CO3 for 3 days immediately following irradiation. On days 1-28 following the last lithium dose, the serum was tested for its CSF activity against both normal non-adherent derived bone marrow target cells and non-adherent marrow cells from mice administered cyclophosphamide (200 mg/kg body weight). Serum was assayed at 0.01, 0.1, 1 and 10 per cent final concentration. No significant difference in the total number of CFU-GM was observed from normal marrow using either serum from irradiated mice or lithium-treated and irradiated mice, although the irradiation did produce a 300 per cent rise in CFU-GM colonies compared to normal serum (days 4 and 10-15). From regenerating marrow, we observed a significant difference (P less than or equal to 0.01) in CFU-GM cultured with serum at 0.1 per cent concentration from irradiated and lithium-treated mice compared to irradiated mice without lithium. The presence of CSF was confirmed by its reduced activity in the presence of anti-(CSF). These results suggest (Li) may increase the sensitivity of CFU-GM to CSF, thereby producing more CFU-GM ultimately providing more circulating granulocytes.

Animals↗
PubMed1985

Regeneration of murine megakaryocytopoiesis and the hematopoietic inductive microenvironment after sublethal whole body irradiation by treatment with an anabolic steroid.

The ability of the anabolic steroid nandrolone decanoate (ND) to increase megakaryocytopoiesis (MP) and the hematopoietic-inductive microenvironment (HIM) after sublethal irradiation was evaluated. Immediately after receiving whole body irradiation (2 Gy) and on the next 2 days, mice were injected with 1.25 mg of ND in propylene glycol intraperitoneally. Irradiated control mice received only vehicle. Compared to controls, drug-treated mice showed a 151% increase in the platelet level on day 14. Drug-treated mice also demonstrated a significant rebound in MP, as colony-forming progenitor stem cells (CFU-Mk) from bone marrow rose to 288% of control by day 8 and from spleen to 599% by day 1 following the last drug injection. In addition, drug-treated mice produced a 286% increase in bone marrow and a 378% in splenic stromal cell colonies on day 5 following drug treatment. These results demonstrate that ND enhances MP and HIM following sublethal irradiation. After hematopoietic suppression, ND may serve to stimulate MP and HIM recovery both at the stem cell level and in peripheral blood.

Anabolic Agents↗
PubMed1985

Dose finding double-blind clinical trial with praziquantel in schistosomiasis japonica patients.

A double-blind clinical trial with praziquantel was carried out. A total of 400 cases was treated with four different dosages, namely, 60, 50, 40 and 30 mg/kg body weight of praziquantel. The drug was given in one day divided into two doses. Identical placebo tablets were used to make up a total of 60 mg/kg. Tolerance was good in all with the exception of one case suffering from asthmatic attack with papule rashes over large area of the body surface. 394 patients were able to be followed up parasitologically six months post-treatment. 79.8%, 71.7%, 78.8% and 70.1% of the patients were negative in the groups with the total dose of 60, 50, 40 and 30 mg/kg respectively. The cure rates as well as the side effects were similar for the four groups. The efficacy was lower than that reported by other authors and the possibility of reinfection was incriminated. In villages with few snails the negative hatching rates in aforementioned four groups were 89.1%, 91.1%, 88.9% and 81.8%, while in villages with abundant snails the rates were 68.2%, 46.5%, 66.7% and 54.8%. The difference between the two areas was statistically significant. Higher efficacy was observed in adults with an average cure rate of 80.0% than in children under 15 years of age, the average cure rate being 57.1%.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1984

Specificity of lithium (Li+) to enhance the production of colony stimulating factor (GM-CSF) from mitogen-stimulated lymphocytes in vitro.

We report here studies demonstrating the ability of Li+ to increase GM-CSF production from both mitogen-induced spleen and thymus cells prepared as serum-free conditioned media (SF-SCCM, SF-TCCM). GM-CSF activity was both a mitogen and Li+ specific mediated event (P less than 0.001-0.001). Identical cultures prepared with either Na, K, Ca, or Mg did not induce GM-CSF activity as compared to Li. No GM-CSF activity was observed in the absence of mitogen. Furthermore, indomethacin (10(-6) M), a potent inhibitor of prostaglandin (PG) synthesis, produced an even greater enhancement in GM-CSF than control cultures prepared without indomethacin. These data indicate Li may enhance GM-CSF production by inhibiting the ability of PG to decrease GM-CSF production. CFU-Mk colony formation was not significantly influenced by any specific cation-induced mitogen (CM), suggesting Li's ability to stimulate megakaryocytopoiesis may be mediated via a more direct stem cell effect. Furthermore, Li-derived (CM) significantly reduced both CFU-E and BFU-E, while those CMs prepared in the presence of K and Ca significantly increased erythroid colony formation. These effects could be mediated via alterations in the production of BPA. These studies demonstrate the unique capacity of cations to influence the differentiation of committed hematopoietic stem cells possibly by modulating the production of such factors required for hematopoietic differentiation.

Animals↗
PubMed1984

The enhancement of committed hematopoietic stem cell colony formation by nandrolone decanoate after sublethal whole body irradiation.

The ability of an anabolic steroid, nandrolone decanoate, to increase committed topoietic stem cell (CFU-gm, CFU-e, and BFU-e) colony formation after sublethal irradiation was evaluated. Immediately after receiving whole body irradiation and on the next two days, each mouse was injected intraperitoneally with nandrolone decanoate (1.25 mg) in propylene glycol. Irradiated control mice received only propylene glycol. Compared to controls, drug-treated mice showed marked peripheral blood leukocytosis and more stable packed red cell volume. Drug-treated mice also demonstrated increased erythropoiesis, as CFU-e/BFU-e concentrations from both marrow (9% to 581%) and spleen (15% to 797%) were elevated. Granulopoiesis was increased similarly, as CFU-gm concentrations from marrow (38% to 685%) and spleen (9% to 373%) were elevated. These results demonstrate that nandrolone decanoate enhances hematopoietic stem cell recovery after sublethal whole body irradiation. This suggests that following hematopoietic suppression, nandrolone decanoate may stimulate the recovery of hematopoiesis at the stem cell level and in peripheral blood.

Animals↗
PubMed1984

Ability of lithium to accelerate the recovery of granulopoiesis after subacute radiation injury.

Lithium stimulates granulopoietic recovery after mice are exposed to 2 Gy. By examining the hematopoietic inductive microenvironment (HIM) using the stromal colony assay, we demonstrate here that lithium, during the two weeks after irradiation, produced less stromal colony suppression than was observed from the irradiated controls. Recovery peaked by day 19 and returned to normal by day 28. This response was also observed in splenic derived stroma. Furthermore, stroma from lithium-irradiated animals supported the in vitro growth of granulocyte-macrophage colonies (CFU-GM) greater than observed from irradiated controls. These data suggest lithium accelerates granulopoietic recovery by first providing for a completely reconstituted and functional HIM.

Animals↗
PubMed1984

The public health importance of African trypanosomiasis in north east Zambia.

A survey for sleeping sickness (Trypanosoma brucei rhodesiense) in villages in the northern Luangwa valley found a point prevalence of parasitaemia of 5.8 per thousand; the incidence of the disease was estimated at about 1% per annum. None of the cases found had sought treatment and pre-symptomatic cases may represent an important reservoir of infection to others. Other frequent parasitemias in the population included malaria (P. falciparum, P. malariae and P. ovale) which is hyperendemic and Dipetalonema perstans.

Adolescent↗
PubMed1984

Clinical trial on furapyrimidone in filariasis.

A clinical trial was carried out with furapyrimidone in treating 51 patients with B. malayi, 159 with W. bancrofti and eight with D. perstans using different dosage schedules. Two hundred and fifty-seven cases of Malayan and bancroftian filariasis were treated with hetrazan for comparison. The results based on the microfilaricidal effects suggest that furapyrimidone possesses similar therapeutic effects of hetrazan on Malayan filariasis at eight-month follow-up, and higher incidences of microfilarial disappearance of W. bancrofti infection (81.3%) at six-month follow-up. The drug was also effective against D. perstans. The side effects consisted of fever and irritation of the digestive tract. Fever may be related to allergic reaction of foreign protein from the dead or dying parasites. The side reactions are similar to those of hetrazan and usually not serious. Comparing the efficacies and side effects of furapyrimidone with different dosage schedules the authors recommend regimens of 15 to 20 mg/kg/day for six days in treating Malayan filariasis and 20 mg/kg/day for seven days in treating bancroftian filariasis.

Adolescent↗
PubMed1984

Hodgkin's disease manifesting as Hashimoto's thyroiditis.

Hodgkin's disease can be manifested in ways other than lymphadenopathy. Two patients had symptoms related to thyroid enlargement and were initially believed to have Hashimoto's thyroiditis on the basis of markedly elevated thyroid antibody titers. Involvement of the thyroid region by Hodgkin's disease was eventually diagnosed.

Adult↗