Localization of thyrotropin-releasing hormone mRNA expression in the rat heart by in situ hybridization histochemistry

Our laboratory has recently detected mRNA of thyrotropin-releasing hormone (TRH) in the rat heart. The density of mRNA for TRH is five-fold higher in the atria than in the left and right ventricle. We also found TRH receptor mRNA and 3H-TRH-binding sites in both ventricles. Cardiac contractility was stimulated after intracoronary administration of TRH. This study was performed to investigate the localization of TRH in the heart. We utilized in situ hybridization histochemistry (ISHH) to localize TRH mRNA expression in the rat heart. ISHH was performed on fresh frozen heart tissue sections which were hybridized with a specific 35S-TRH oligo probe and subsequently processed by autoradiography. The autoradiographic signals corresponding to TRH mRNA were analyzed with an image program. For positive controls TRH mRNA was identified in the hypothalamic paraventricular nucleus. This test confirms the specificity of the TRH oligo probe. Cardiac hybridization signals were observed predominantly in the atria and localized preferentially in atrial connective tissues, vascular adventitia and atrial cardiomyocytes. No hybridization signals were found in ventricular cardiomyocytes. These observations suggest that TRH is synthesized in atrial myocytes and atrial vascular structures. Based on studies which show synthesis of the TRH receptors in ventricular cardiomyocytes, we hypothesize that atrial TRH is an endocrine source for the stimulation of ventricular contractility and that endothelial and adventitial TRH may play a role(s) in the regulation of the growth and/or vasomotor tome of the cardiac vascular system.

[Evaluation of acute flaccid paralysis (AFP) surveillance system in 1994]

Increased by 40.2% compared with 1993, 3142 acute flaccidparalysis cases were reported from AFP surveillance system in 1994. A total number of 1297 counties had AFP cases reported, accounting for 45.1% of total amount of counties. Out of 3142 AFP cases, 307 were confirmed, coming from 225 counties. For children under 15 years old, the reported AFP incidence was 1.1/10(5), non-polio AFP rate was 0.83/10(5), much higher than 0.37/10(5), in 1993. 48.5% of the total AFP cases had double stool specimen taken within 0-14 days after paralysis. 79% AFP cases had been investigated within 48 hours after being reported. Some of the major monitoring indicators of AFP surveillance system were close to the WHO criterion, but the percentage of AFP cases reported within 48 hours of careseeking and AFP cases with follow-up visit after 60-70 days of paralysis were very low. Furthermore, 77.9% of the confirmed cases were diagnosea clinically by residual paralysis, so did the 46.4% of discarded cases. It is in urgent need to increase the percentage of cases classified by laboratory test.

Use of yeast artificial chromosomes (YACs) in studies of mammalian development: production of beta-globin locus YAC mice carrying human globin developmental mutants

To test whether yeast artificial chromosomes (YACs) can be used in the investigation of mammalian development, we analyzed the phenotypes of transgenic mice carrying two types of beta-globin locus YAC developmental mutants: (i) mice carrying a G-->A transition at position -117 of the A gamma gene, which is responsible for the Greek A gamma form of hereditary persistence of fetal hemoglobin (HPFH), and (ii) beta-globin locus YAC transgenic lines carrying delta- and beta-globin gene deletions with 5' breakpoints similar to those of deletional HPFH and delta beta-thalassemia syndromes. The mice carrying the -117 A gamma G-->A mutation displayed a delayed gamma- to beta-globin gene switch and continued to express A gamma-globin chains in the adult stage of development as expected for carriers of Greek HPFH, indicating that the YAC/transgenic mouse system allows the analysis of the developmental role of cis-acting motifs. The analysis of mice carrying 3' deletions first provided evidence in support of the hypothesis that imported enhancers are responsible for the phenotypes of deletional HPFH and second indicated that autonomous silencing is the primary mechanism for turning off the gamma-globin genes in the adult. Collectively, our results suggest that transgenic mice carrying YAC mutations provide a useful model for the analysis of the control of gene expression during development.

Ligand (T3) dependent and independent effects of thyroid hormone receptors upon human TRH gene transcription in neuroblastoma cells

Thyrotropin releasing hormone (TRH) gene is regulated negatively at the transcriptional level by thyroid hormone (T3) in rat anterior hypothalamus. The actions of T3 upon other target genes are known to be mediated through the thyroid hormone receptors (TR), TR alpha and TR beta. To explore whether the inhibitory regulation of human (h) TRH gene transcription by T3 is TR isoform specific and whether TRH gene transcription can be modulated as well by unliganded TR isoforms, transient gene expression studies have been carried out using hTRH-luciferase (TRH-Luc) chimeric constructs and TR expression constructs, co-transfected into a human neuroblastoma cell line (HTB-11). Data herein demonstrate T3-dependent inhibitory regulation of the hTRH gene promoter by TR-T3 complexes. Moreover, significant inhibition (39%-60%) could be achieved by T3 bound to either hTR alpha 1, hTR beta 1, or rTR beta 1, beta 2 and was comparable quantitatively, indicating an absence of TR isoform specificity for T3 inhibition. Conversely, basal promoter activity of the hTRH gene could be activated significantly by unliganded hTR alpha 1, beta 1, rTR beta 1, and beta 2 (150% to 334%), but not by hTR alpha 2. Thus, TRs appear to exert opposite effects on hTRH gene transcription, depending on the presence or absence of ligand (T3). These dual effects of TR suggest that the addition of the T3 ligand effects conformational changes that can abrogate the initiation of transcription.

Pneumoconiosis: the changes of peripheral airways

Ultrathin bronchofiberscope (Olympus BF-1.8T) was applied to the observation of the peripheral airways of total 87 cases, including 73 cases of quartz-exposed and asbestos-exposed workers with/without pneumoconiosis (exposure groups), and 14 cases of controls. The changes of peripheral airways in exposure group of non-smokers was found, mainly to be pigmentation, elevation, irregularity and lustlessness on the surface of the bronchiole walls, and predominantly stenosis and ectasis of the lumen. The detectable rate was higher in peripheral airways than in central airways. Some changes existed in early stage and some had a tendency of increasing detectable rate with category progressing. Some factors such as smoking could influence the results of analysis.

[A comparison between diltiazem SR and diltiazem HCL in the treatment of angina pectoris]

This study included 168 patients with angina pectoris, who were divided into two groups, the diltiazem SR (No. 88) group and diltiazem HCL (No. 80) group. The two groups were comparable in age and duration of coronary heart disease. The results were as follows: (1) The total clinical effect of diltiazem SR (94.3%) was slightly greater than that of diltiazem HCL (82.5%), the effect in ECG improvement was 53.3% and 53.4% respectively. (2) The rate of adverse effect was 12.5% in diltiazem SR group and 14.4% in diltiazem HCL group. It is concluded that the two different types of diltiazem have similar effect in the treatment of angina pectoris. However, it is more convenient to take diltiazem SR than diltiazem HCL as the former needs only twice a day.

[The choice of treatment in acute hemorrhagic necrotic pancreatitis: medical or surgical?]

In recent ten years, physicians and surgeons in Beijing Tong Ren Hospital cooperated well in the treatment of acute hemorrhagic necrotic pancreatitis. Twenty four cases were chosen to determine whether medical conservative or surgical operative treatment should be given. In the surgical operation group there were fourteen cases. Twelve cases survived and the remaining two died. In the medical conservative group only one of the ten cases died. The overall mortality of the twenty four cases of acute hemorrhagic pancreatitis was 12.5%. In our study, the indications for operation were as follows: (1) Presence of more than five positive diagnostic criteria. (2) Accompaniment of gall stone. (3) Inability to differentiate with other acute surgical abdominal emergencies such as intestinal obstruction.

Loss of thyroid hormone receptor activity in primary cultured rat hepatocytes is reversed by 2-mercaptoethanol

In primary cultures of rat hepatocytes, specific thyroid-hormone-binding activity diminished with time and was hardly detectable at 24 h. In accordance with the loss of 3,5,3'-tri-iodothyronine (T3) binding, responses to the hormone disappeared, as indicated by low induction of the thyroid-hormone-responsive gene S14. In contrast, thyroid hormone receptor proteins were present, as determined by immunostaining with a specific antibody against the receptor. Thus the loss of T3 binding was due to receptor inactivation. After various attempts to restore the T3-binding activity, we found that 2-mercaptoethanol, a reducing agent, when added to the culture medium restored the hormone binding activity in a dose- and time-dependent manner. The observed kinetics and experiments using cycloheximide suggested that mercaptoethanol prevented inactivation of the newly synthesized receptors. Oxidoreductive conditions within cells may have a role in determining the level of activity of thyroid hormone receptors.

[Regulatory effect of insulin on glucocorticoid receptor in human peripheral leukocytes]

The regulatory effect of insulin on the specific binding power of glucocorticoid receptor (GR) of human leukocytes was assessed by the unoccupied receptor sites capable of combining with [3H] labelled dexamethasone measured at 3 and 24 h after incubation with various concentrations of insulin added to the medium. After 3 h incubation the specific binding power with [3H] Dex was decreased by 23.3 +/- 10.0, 32.2 +/- 13.2 and 54.3 +/- 9.2% (P greater than 0.05, P greater than 0.05 and P less than 0.01 as compared with the control value of 100 in the absence of insulin) respectively in the presence of 20 mU/L (physiological testing concentration), 200 mU/L (physiological upper limit) and 2,000 mU/L (pharmacological concentration) insulin in the incubation medium. After 24 h incubation the decrease of these values increased respectively to 43.5 +/- 19.0, 56.1 +/- 20.7 and 80.2 +/- 15.5 (P less than 0.05, P less than 0.01 and P less than 0.01 compared with control). Thus the inhibitory effect of insulin on the GR binding power is both dose- and time-dependent, which strongly suggests that GR is tonically controlled by insulin concentration change under physiological conditions.

[Effect of combined treatment of diltiazem and digoxin on serum digoxin concentration]

Diltiazem is one of the effective calcium channel blocking agents. Up to now it has not been reported in our country that whether the combined use of digoxin and diltiazem can increase the serum concentration of digoxin The results of a study of ten cases with chronic congestive heart failure showed that diltiazem can increase the serum concentration of digoxin from 38.7% to 49.6%. Four of the ten cases appeared to have signs of digitalis poisoning in the electrocardiogram.

Beta-globin locus activation regions: conservation of organization, structure, and function

The human beta-globin locus activation region (LAR) comprises four erythroid-specific DNase I hypersensitive sites (I-IV) thought to be largely responsible for activating the beta-globin domain and facilitating high-level erythroid-specific globin gene expression. We identified the goat beta-globin LAR, determined 10.2 kilobases of its sequence, and demonstrated its function in transgenic mice. The human and goat LARs share 6.5 kilobases of homologous sequences that are as highly conserved as the epsilon-globin gene promoters. Furthermore, the overall spatial organization of the two LARs has been conserved. These results suggest that the functionally relevant regions of the LAR are large and that in addition to their primary structure, the spatial relationship of the conserved elements is important for LAR function.

Restriction enzyme SnaBI is sensitive to methylation of cytosine within its recognition sequence

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Fatty acyl-CoAs are potent inhibitors of the nuclear thyroid hormone receptor in vitro

We report that long-chain fatty acyl-CoAs are potent inhibitors of the thyroid hormone (T3) receptor isolated from rat liver nuclei. Both saturated and unsaturated fatty acyl-CoAs were similarly potent. Fifty per cent inhibition of T3 binding by the receptor was observed at an oleoyl-CoA concentration as low as 1.3 microM, and the affinity of oleoyl-CoA for the receptor (Ki) was estimated to be 0.45 microM. Fatty acyl-CoAs also promoted dissociation of the hormone bound to the receptor. The action of fatty acyl-CoAs was competitive for the hormone binding site, resulting in a reduction in the receptor's affinity for T3. These observations suggest that fatty acyl-CoAs modulate the binding of the thyroid hormone to its nuclear receptor, in vitro. Whether or not such events occur in vivo remains to be determined.

Application of partial restriction procedure in both shotgun and non-random strategies for nucleotide sequencing

Partial digestion of a target DNA fragment with 4-bp-recognition restriction enzymes followed by a forced ligation to an M13 vector was employed for the construction of a subfragment library. The library can be used for either shotgun or non-random nucleotide sequencing. Application of the partial digests generated with the 4-bp recognition restriction enzymes instead of DNase I in the improved non-random strategy for nucleotide sequencing (Li and Wu, 1987) made the procedure as easy as that of the random strategy. The library can also be used in shotgun nucleotide sequencing directly, and few self-ligated subfragments were found. The usefulness of this procedure was demonstrated by the sequencing of a goat 6.5-kb EcoRI fragment, which is located 5' to the epsilon globin gene.

An analysis of postsynaptic potentials of tectal neurons of the frog: correlation with impulses recorded from the terminals of retinotectal afferents

The purpose of this study is to examine the synaptic action between terminals of retinal ganglion cell axons and tectal neurons. To accomplish this, an extracellular single unit identified as retinotectal fiber was first isolated from the superficial layer of the optic tectum and intracellular responses were recorded from a tectal neuron in the vicinity of the extracellular recording electrode. "On-off" retinal fibers and both E-E (EPSP at "on" and "off" of diffuse light) and EI-EI type (EPSP-IPSP combination at "on" and "off" of diffuse light) tectal neurons were selected for the pre- and postsynaptic pair. Postsynaptic responses to a small moving square were averaged by triggering with the isolated presynaptic impulses. The latency of the resultant EPSPs indicated that most of the E-E and EI-EI type tectal neurons were monosynaptically activated by "on-off" retinal fibers. One of the E-E type tectal neurons was identified as a large ganglionic neuron in layer 8.

A versatile and simplified non-random strategy for nucleotide sequencing

We describe a versatile and simplified non-random strategy for nucleotide sequencing. This procedure avoids exposure of the vector DNA to endo- or exonucleases during construction of the subfragment library. The advantages resulting from this strategy are: (1) minimal manipulation in construction of the subfragment library, (2) no need for compatible restriction sites, (3) no insert size limitation, (4) can be used with both chemical and enzymatic sequencing methods. Hence, the procedure provides simplicity, universality and versatility for non-random nucleotide sequencing. We demonstrate the usefulness of this procedure by obtaining the nucleotide sequence of a goat 3.7-kb EcoRI fragment, which is 5' of the epsilon globin gene.

Restriction endonucleases from three strains of Haemophilus influenzae

The restriction endonucleases, Hin P1 I1), Hin S1 I and Hin S2 I are isolated from three strains of Haemophilus influenzae respectively. By polymin P treatment, ammonium sulphate, precipitation and column chromatography on phosphocellulose and on heparin-Sepharose Hin P1 I is partially purified. No contaminating deoxyribonuclease activities have been detected in this purified enzyme preparation. The fact that the digestion patterns of Hin P2 I and Hha I on phage lambda, plasmids ColE1 an pBR 322 DNAs are identical that they are isoschizomers but theri splitting sites are different. The banding patterns of Hin S1 I and Hin S2 I are also the same as that of Hha I.