Search PubMed⌕ Search

Biomedical subjects

J Ma

Publications and source records attributed to J Ma.

At least 595 records · Page 33Linked to original sources
PubMed1990

Klinefelter's syndrome and primary central nervous system lymphoma.

Klinefelter's syndrome is known to be associated with various malignancies including male breast cancer and germ cell tumour. We report a patient with Klinefelter's syndrome who developed a primary B-cell lymphoma of the central nervous system (CNS). To the best of our knowledge, this is the first case of primary CNS lymphoma in Klinefelter's syndrome.

Adult↗
PubMed1990

Association of transport-defective light chains with immunoglobulin heavy chain binding protein.

Immunoglobulin light chains are usually secreted from cells when they are synthesized alone or in molar excess of heavy chains, but, there have been reports of nonsecreted light chains. We wished to determine whether immunoglobulin heavy chain binding protein (BiP), which blocks the transport of free heavy chains, might be responsible for the lack of secretion of some light chains. In two murine lymphoid cell lines that synthesize but do not secrete immunoglobulin light chains, the free light chain polymers were found bound to BiP. Examination of 20 other cell lines and hybridomas failed to disclose any cells synthesizing free or excess light chains that associated with BiP, in all cases the free light chains were secreted as dimers. Despite their association with BiP and their blocked secretion, the aberrant light chains could combine with heavy chains and could be secreted as intact Ig molecules. Thus, while light chains do not usually express signals which allow them to bind to BiP, it appears that such signals can be expressed on certain light chains, resulting in their combination with BiP and blocked secretion. When single chain mutant cell lines are isolated from parental lines producing both heavy and light chains, they are almost always light chain producers suggesting that free heavy chains are much more toxic than free light chains. In both PC700 and P3X63Ag cells, however, clones that have lost either heavy chains or transport-defective light chains are present at the same frequency. Our findings that the light chains in both of these lines are associated with BiP raise the possibility that BiP actually contributes to heavy chain toxicity instead of preventing it.

Animals↗
PubMed1990

Direct binding of verapamil to the ryanodine receptor channel of sarcoplasmic reticulum.

Radioligand binding experiments and single channel recordings demonstrate that verapamil interacts with the ryanodine receptor Ca2+ release channel of the sarcoplasmic reticulum of rabbit skeletal muscle. In isolated triads, verapamil decreased binding of [3H]Ryanodine with an IC50 of approximately 8 microM at an optimal pH 8.5 and pCa 4.3. Nitrendipine and d-cis-diltiazem did not interfere with binding of [3H]Ryanodine to triads, suggesting that the action of verapamil does not involve the dihydropyridine receptor. Single channel recordings showed that verapamil blocked Ca2+ release channels by decreasing open probability, duration of open events, and number of events per unit time. A direct interaction of verapamil with the ryanodine receptor peptide was demonstrated after purification of the approximately 400 kDa receptor protein from Chaps-solubilized triads. The purified receptor displayed high affinity for [3H]Ryanodine with a Kd of approximately 5 nM and a Bmax of approximately 400 pmol/mg. Verapamil and D600 decreased [3H]Ryanodine binding noncompetitively by reducing the Bmax. Thus the presence of binding sites for phenylalkylamines in the Ca2+ release channel was confirmed. Verapamil blockade of Ca2+ release channels may explain some of the paralyzing effects of phenylalkylamines observed during excitation-contraction coupling of skeletal muscle.

Animals↗
PubMed1990

Opposing regulatory functions of positive and negative elements in UASG control transcription of the yeast GAL genes.

The yeast GAL1 and GAL10 genes are transcribed at a remarkably low basal level when galactose is unavailable and are induced by over 4 orders of magnitude when it becomes available. Approximately six negative control elements (designated GAL operators GALO1 to GALO6) are located adjacent to or overlapping four binding sites for the transcription activator GAL4 in the GAL upstream activating sequence UASG. The negative control elements contribute to the broad range of inducibility of GAL1 and GAL10 by inhibiting two GAL4/galactose-independent activating elements (GAE1 and GAE2) in UASG. In turn, multiple GAL4-binding sites in UASG are necessary for GAL4 to overcome repression by the negative control elements under fully inducing conditions. When glucose in addition to galactose is available (repressing conditions), the ability of GAL4 to activate transcription is diminished as a result of its reduced affinity for DNA and the reduced availability of inducer. Under these conditions, the negative control elements inhibit transcriptional activation from the glucose-attenuated GAL4 sites, thus accounting at least in part for glucose repression acting in cis. A normal part of transcriptional regulation of the GAL1 and GAL10 genes, therefore, appears to involve a balance between the opposing functions of positive and negative control elements.

Base Sequence↗
PubMed1990

[Studies on man-cattle-man infection cycle of Sarcocystis hominis in Yunnan].

The present paper reports on the results of an experimental study on man-cattle-man infection of Sarcocystis hominis, found in Yunnan Province. About ten thousand sporocysts collected from the feces of persons naturally infected with Sarcocystis hominis were fed to a calf, which was dissected 150 days later. Numerous cysts of Sarcocystis hominis were found in the cardiac and skeletal muscles. By light microscopy, the cyst wall of fresh preparation showed numerous thick, finger-like projections, with maximum length of 7.9 microns. By electron microscopy, the cyst had a regularly folded, with primary wall forming palisade-like protrusions. Numerous sharp invaginations found in the protrusions were sawtooth-shaped, covering the whole surface of the protrusions. No fine fibrils were observed within the zone of ground substance beneath the primary cyst wall. Two rhesus monkeys were fed with beef infected with Sarcocystis hominis and sporocysts and oocysts were found in their feces 29 and 31 days later, the patent period of sporocyst excretion being 5 and 7 days, respectively. The senior author had taken voluntarily 60 g beef of the experimentally infected calf, and presented clinical symptoms such as anaemia, abdominal pain, diarrhoea, fatigue and dizziness on d3 post infection with sporocysts and oocysts found in the feces on d8. The patent period of sporocyst excretion was more than 42 days. The mean size of 50 sporocysts was 11.90 +/- 0.04 x 15.88 +/- 0.03 micron and that of 50 oocysts, 15.56 +/- 0.05 x 19.76 +/- 0.04 micron. On d50 he took acetylspiramycin tablets, the initial dose being 0.4 g, followed by 0.2g qid. for 15 days.(ABSTRACT TRUNCATED AT 250 WORDS)

Animal Feed↗
PubMed1990

[Analysis of brain CT in 120 patients with human cysticercosis].

A study on brain CT was made in 120 patients of human cysticercosis, which is a rare disease in Japan and clinical symptoms and laboratory data for the diagnosis were also discussed. From the point of therapeutic view, we proposed a new differentiation on brain CT of human cysticercosis, which is divided into two groups according to the alive or dead parasite. Furthermore, we proposed a new type named multiple large and small cysts type on brain CT. The idea of diagnostic standard was made integrating brain CT image, clinical symptoms and laboratory data.

Adolescent↗
PubMed1990

[Antitumor action of lignum sappan].

The aqueous extract of lignum sappan can kill cell lines of HL-60, K562, L929 and Yac-1 at the concentration of 2 microliters/ml. The survival time of mice bearing EAC is increased by 185% (P less than 0.01) by ip 0.2 ml/mouse x 7d. The three-stage sequential test standard can be passed smoothly.

Animals↗
PubMed1989

Rescue of bicoid mutant Drosophila embryos by bicoid fusion proteins containing heterologous activating sequences.

The maternal gene bicoid (bcd) determines pattern in the anterior half of the Drosophila embryo. It is reported here that the injection of bcd mutant embryos with messenger RNAs that encode proteins consisting of heterologous acidic transcriptional activating sequences fused to the DNA-binding portion of the bcd gene product, can completely restore the anterior pattern of the embryo.

Animals↗
PubMed1989

Mucin immunohistochemistry of the columnar epithelium of the oesophagus (Barrett's oesophagus).

Columnar cell lined lower oesophagus (CELLO), often considered to be a precancerous lesion, is characterized by a glandular mucosa with a predominance of sulphomucins in the specialized epithelium. This histochemical abnormality can be correlated with abnormal differentiation which may also be studied by anti-mucus antibodies (anti-M1, anti-M3, anti-SIMA, anti-LIMA). The purpose of this prospective study is to define the mucin profile in a large population of CELLO by immunohistochemistry and to compare it with the results of histochemistry. Biopsies of 79 patients with reflux oesophagitis were included. Thirty-eight had CELLO and 41 had a histologically normal cardia. Six surgical specimens of oesophageal adenocarcinomas were also included. The histochemical methods confirmed the preponderance (57.9%) of type III intestinal metaplasia (IM) found in 57.9% of cases. The immunohistochemical methods showed a similar antigenic profile of type II and III IM with positivity of anti-SIMA and anti-M3 antibodies in the goblet cells, and positivity of anti-LIMA antibodies in both the goblet and intermediate cells of the specialized epithelium. The mucus secreting cells of the oesophageal adenocarcinomas had the same immunohistochemical profile. These results are similar to those of Filipe et al. in type II and III IM surrounding gastric adenocarcinomas. Immunohistochemical methods allow us to subdivide type II and type III IM into 2 subgroups according to the positivity or negativity of the anti-LIMA antibodies in the intermediate cells. Among the 41 normal cardias in patients with reflux oesophagitis, 10 contain sulphomucin secreting cells positive with anti-LIMA antibodies. We suggest that this anti-LIMA positivity may be a step preceding type III IM in specialized epithelium.

Barrett Esophagus↗
PubMed1989

Prevalence of cryptosporidiosis in patients undergoing endoscopy: evidence for an asymptomatic carrier state.

PURPOSE: We sought to determine the presence of the parasite cryptosporidium in the duodenal aspirates of patients undergoing routine upper gastrointestinal endoscopy. PATIENTS AND METHODS: The study consisted of 169 patients undergoing upper endoscopy or endoscopic retrograde cholangiopancreatography. Immunocompromised patients were not included in the study population. Samples were aspirated from the second portion of the duodenum. Biopsy specimens were also obtained. Three randomly passed stool samples were obtained from 75% of the patients who were found to have cryptosporidium in the duodenum. RESULTS: Overall, cryptosporidium oocysts were identified in 12.7% of patients. There was no significant difference in the prevalence of the parasite in any subgroup of procedure or symptom complex. Half of those (46.7%) with positive aspirates had demonstrable cryptosporidium in stool samples, although none of the patients had diarrhea. No patient had detectable cryptosporidium in biopsy samples of the duodenum. CONCLUSION: The findings suggest a surprisingly high asymptomatic carrier rate for cryptosporidium.

Carrier State↗
PubMed1989

[Study of logistic curve fitting for primary liver cancer death rate in Chengdu].

Logistic curve was used for fitting primary liver cancer (PLC) age-specific death rate in Chengdu. The results showed that the age-specific death rate from 1981 to 1986 in Chengdu (population about 4,000,000) was satisfactorily fitted by logistic curve in male, female and total (P less than 0.01). The R2s were 0.9885, 0.9912 and 0.9974, respectively. Velocity analysis of death rate showed that the increasing peak was in the group of age 40-60 for male and 50-65 for female. Male's velocity and slope of death rate were higher and steeper than female's. These results are consistent with the feature of logistic curve and parameters obtained from logistic curve fitting in this study. The age-specific death rate by sex for every year from 1981 to 1986 was fitted very well (P less than 0.01). R2s for male and female were 0.9415 +/- 0.044 and 0.9056 +/- 0.048, respectively.

Age Factors↗
PubMed1989

[Catalytic model analysis of HAV and HBV infection rate in a PLA population].

Mathematical model can be used to express the quantitative relationship between the factors of epidemiologic processes. In this paper, we tried to analyze the data of HAV and HBV infection rates obtained in a cross-section study in a Navy aviation school in December 1983, using simple and reversible catalytic models. It was shown that the expected HAV prevalence rate was not significantly different from the observed HAV infection rate and the observed incidence density of HAV new infection (111.8/1000 person-year) found during follow-up period of one and-a-half years was nearly identical to the theoretical value (111.7/100 person-year). The result of reversible model fitted the HBV prevalence rate well, not significantly different from the data of the cross section study, but the revalue was a little different from that observed in the follow-up period. The results suggest that mathematical model is very useful in the analysis of the HAV and HBV prevalence rates in a fixed population. The catalytic model can be used to predict the average infection rates. To make the models fitting better, a long-time follow-up study or multivariable analysis is required and the formula needs further improvement.

Adolescent↗