CD4 expressed on earliest T-lineage precursor cells in the adult murine thymus

A continuous but low input of stem cells or 'prothymocytes' is necessary to maintain T-cell development in the adult thymus, but the colonizing cell has not been characterized. Precursors of T cells have been found in the minor CD4-8- population of thymocytes, but even the earliest cells of this population already have partially rearranged T-cell antigen receptor (TCR) genes. We now demonstrate that the thymus contains a minute population of lymphoid cells similar in some but not all respects to bone marrow-derived haemopoietic stem cells. This population has TCR genes in a germline state. It gives a slow but extensive reconstitution of both alpha beta and gamma delta lineages on transfer into an irradiated thymus, with kinetics indicating that it includes the earliest intrathymic precursor cells so far isolated. Surprisingly, these cells express low surface levels of the mature T-cell marker CD4.

Cyclic nucleotide phosphodiesterase of Dictyostelium discoideum and its glycoprotein inhibitor: structure and expression of their genes

The genes coding for the cyclic nucleotide phosphodiesterase (PD) and the PD inhibitory glycoprotein (PDI) have been cloned and characterized. The PDI gene was isolated as a 1.6 kb genomic fragment, which included the coding sequence containing two small introns and 510 nucleotides of non-translated 5' sequence. From the deduced amino acid sequence we predict a protein with a molecular weight (MW) of 26,000 that, in agreement with previous data, contains 15% cysteine residues. Genomic Southern blot analysis indicates that only one gene encodes the inhibitor. Northern blot analysis shows a single transcript of 0.95 kb. The PDI gene is expressed early in development with little transcript remaining following aggregation. The appearance of PDI mRNA is prevented by the presence of cAMP, but when cAMP is removed the transcript appears within 30 minutes. When cAMP is applied to cells expressing PDI the transcript disappears with a half-life of less than 30 minutes. The PD gene of D. discoideum is transcribed into three mRNAs: a 1.9 kb mRNA specific for growth, a 2.4 kb mRNA specific for aggregation, and a 2.2 kb mRNA specific for late development. The 2.2 kb mRNA is also specific for prestalk cells, and is induced by differentiation-inducing factor. All three mRNAs contain the same coding sequence, and differ only in their 5' non-coding sequences. Each mRNA is transcribed from a different promoter, and by using the chloramphenicol acyltransferase gene as a reporter, we have shown that each promoter displays the same regulation as its cognate mRNA.(ABSTRACT TRUNCATED AT 250 WORDS)

Gated cardiac blood pool studies in atrial fibrillation: role of cycle length windowing

Cycle length windowing is gaining increasing acceptance in gated blood pool imaging of patients with atrial fibrillation (AF). The goals of this study were: to assess differences of ejection fraction (EF) in AF with and without windowing and to determine how EF varied with cycle length in patients with AF. Twenty patients with AF were prospectively studied by gated blood pool imaging, with simultaneous collection in each patient of 5-7 studies with cycle length windows spanning the cycle length histogram. Each window accepted beats of only a narrow range of cycle lengths. EF was determined for each of the narrow cycle length windows as well as for the entire gated blood pool study without cycle length windowing. For every patient an average of the windowed EFs was compared with the non-windowed EF. EF values were similar (mean windowed: 46.6; non-windowed: 45.5; P = 0.16), and there was a good correlation between the two techniques (r = 0.97). The data were then examined for a relationship of EF with cycle length. The difference from average windowed EF (delta EF) was calculated for each window and plotted vs. the cycle length of the center of each window. No predictable linear or nonlinear relationship of delta EF with window position was observed. Lack of predictable variation of EF with cycle length is likely due to lack of a predictable amount of ventricular filling for a given cycle length, as the amount of diastolic filling in AF depends on the random cycle length of the preceding beat.(ABSTRACT TRUNCATED AT 250 WORDS)

2,3,7,8-Tetrachlorodibenzo-p-dioxin induces cytochrome P450IA1 enzyme activity by activating transcription of the corresponding gene

We have reviewed the transcriptional regulation of the CYP1A1 gene, which encodes the cytochrome P450IA1 enzyme. TCDD induces CYP1A1 transcription via a receptor- and enhancer-dependent mechanism that involves multiple protein-DNA interactions. The system provides an example of enzyme regulation at the level of gene transcription.

[Visual pigment genes for color vision defects]

Applying recombinant DNA techniques, the structures of red pigment gene (RPG) and green pigment gene (GPG) were analyzed for 43 patients with protan or deutan (including 3 females), 4 normal relatives and 3 carriers out of 3 families, as well as 11 normal controls. Abnormality of RPG was detected in all 19 protan and that of GPG was found in 14 out of 24 deutan. In about 80% (32/40) of protan and deutan the changing of exon 5 for RPG or GPG was discovered. In protan the normal RPG was replaced by a 5' red -3' green hybrid gene. Some of the deutan had no GPG, some had 5' green -3' red hybrid gene with or without GPG. Furthermore, the exon 5 of RPG and GPG was amplified by polymerase chain reaction (PCR) and further analyzed by Rsa I digestion. The results for PCR are identical to that of Southern blot hybridization.

[The visual evoked potentials in ischemic optic neuropathy]

In this study the pattern-reversal stimulation was used for analysing the clinical VEP in 27 cases (37 eyes) of ischemic optic neuropathy (ION), and combined uses of visual field (VF) and contrast sensitivity (CS) examinations were compared and observed with 3 kinds of spatial frequencies (60', 30', 15' check size), VEP in the eyes of ION displayed decrease in amplitude as a dominant manifestation accompanied by the slight increase of latency period. The abnormal latency and amplitude were 83.5% and 81.3% respectively. The decreased CS in the ION eyes was appeared mainly in the stimulation of middle and high frequencies or all frequency bands. There was a significant correlation between the VEP amplitude and CS in the patients with ION. The quadrant VF defect and bow-shaped scotoma were displayed in majority of the cases. Abnormal VEP was shown to be related to the central VF impaired. Among these patients, 7 cases (8 eyes) were followed up with VEP, however the VEP amplitude was shown decreasing somewhat compared with first exam. The results indicated that the ION was responsible for many visual function damages.

[Visual pigment genes for color vision defects]

Applying recombinant DNA techniques, the structures of red pigment gene (RPG) and green pigment gene (GPG) were analyzed for 43 patients with protan or deutan (including 3 females), 4 normal relatives and 3 carriers out of 3 families, as well as 11 normal controls. Abnormality of RPG was detected in all 19 protan and that of GPG was found in 14 out of 24 deutan. In about 80% (32/40) of protan and deutan the changing of exon 5 for RPG or GPG was discovered. In protan the normal RPG was replaced by a 5' red -3' green hybrid gene. Some of the deutan had no GPG, some had 5' green -3' red hybrid gene with or without GPG. Furthermore, the exon 5 of RPG and GPG was amplified by polymerase chain reaction (PCR) and further analyzed by Rsa I digestion. The results for PCR are identical to that of Southern blot hybridization.

[The visual-vestibular interaction in normal subjects]

Full-field optokinetic nystagmus (OKN) at constant speed of 40 0/s and 60 0/s, vestibular ocular reflex (VOR) (sinusoidal 0.2 Hz, 60 0/s peak velocity) with different background (light and dark) and VOR-fix were observed in 72 normal subjects (144 normal eyes). The gain, FCV and DP of OKN, VVOR, VOR were also analysed. The gain of OKN is reduced accompanied with stimulation increasing, while the FCV is increased. The gain of VVOR is 1.08 +/- 0.09 (X +/- SD), while the gain of VOR is 0.64 +/- 0.09. The FCV of VOR is much reduced than that of VVOR. The FCV in the groups under 30 years of age are much faster than the groups above 30 years of age. The VOR--fix gain is 0.05 +/- 0.04. The DP of OKN, VVOR, and VOR are 0.05 +/- 0.04. The results showed an co-operation between visual and vestibular systems and the results also suggested that the series methods of visual-vestibular interaction (OKN, VVOR, VOR, VOR-fix) might be useful in eye movement examination.

[The visual-vestibular interaction in normal subjects]

Full-field optokinetic nystagmus (OKN) at constant speed of 40 degrees/s and 60 degrees/s, vestibular ocular reflex (VOR) (sinusoidal 0.2Hz, 60 degrees/s peak velocity) with different background (light and dark) and VOR-fix were observed in 72 normal subjects (144 normal eyes). The gain, FCV and DP of OKN, VVOR, VOR were also analysed. The gain of OKN is reduced accompanied with stimulation increasing, while the FCV is increased. The gain of VVOR is 1.08 +/- 0.09(mean +/- SD), while the gain of VOR is 0.64 +/- 0.09. The FCV of VOR is much reduced than that of VVOR. The FCV in the groups under 30 years of age are much faster than the groups above 30 years of age. The VOR-fix gain is 0.05 +/- 0.04. The DP of OKN, VVOR, and VOR are 0.05 +/- 0.04. The results showed an co-operation between visual and vestibular systems and the results also suggested that the series methods of visual-vestibular interaction (OKN, VVOR, VOR, VOR-fix) might be useful in eye movement examination.

[Study on several systems used for chemiluminescent determination of horseradish peroxidase]

Four systems were studied used for chemiluminescent determination of HRP and the determination conditions optimized. In luminol-H2O2 (NaOH) system, HRP was determined conveniently in the range of 0.05-4 pmol, with a correlation coefficient of 0.998 for the linear log-log equation and a limit of detection of 16 fmol HRP. In pyrogallol-H2O2 (pH 6.5) system, 0.1-100 pmol of HRP were determined, based on three log-log regression equations with correlation coefficients of 0.997, 0.994 and 0.999, respectively, and limits of detection of 3-17 fmol HRP. Luminol-H2O2-para iodophenol system was used to determine HRP in the range to 10-50 fmol, based on the chemiluminescence intensity at 1 min and the correlation coefficient of the log-log equation being 0.996 with a limit of detection of 10 fmol HRP. When p-hydroxybiphenyl was used to take the place of p-iodophenol and the chemiluminescence intensity at 1 min or 3 min measured, 6-40 fmol HRP were determined with a correlation coefficient of 0.994 or 0.995 for the log-log equation and a limit of detection of 6.5 or 3.3 fmol HRP.

Identification of a nucleotide exchange-promoting activity for p21ras

The biological activity of proteins encoded by the ras family of oncogenes is dependent on whether they are bound to GTP or GDP: the type of nucleotide bound is dependent on the rate of GTP hydrolysis (promoted by the GTPase-activating protein, GAP) and the rate of nucleotide exchange with cytosolic pools. A protein that stimulates the rate of exchange of guanine nucleotide on p21ras has been identified and characterized in cytoplasmic extracts of human placenta. The exchange-promoting protein runs on a gel filtration column with an apparent relative molecular weight of about 60,000. It is sensitive to heat and to trypsin. The exchange-promoting protein acts reversibly and does not cause degradation of p21ras. It is inactive towards the alpha subunit of a heterotrimeric GTP-binding protein (Go alpha) but acts on a large number of different mutant ras proteins, including transforming and effector mutants that are insensitive to the action of GAP. This protein, which we have termed REP (ras exchange-promoting), has the characteristics expected of a physiological activator of p21ras in cellular growth-signal-transduction pathways.

A developmentally regulated and cAMP-repressible gene of Dictyostelium discoideum: cloning and expression of the gene encoding cyclic nucleotide phosphodiesterase inhibitor

A 1.6-kb genomic fragment containing the coding region for the inhibitor (PDI) of cyclic nucleotide phosphodiesterase (PD) was isolated and sequenced. The genomic sequence includes 510 nucleotides (nt) of 5'-noncoding sequence and the full coding sequence, which contains two small introns. From the deduced amino acid (aa) sequence we predict a 26-kDa protein that, in agreement with previous data, contains approximately 15% Cys residues. The PDI possesses a hydrophobic leader sequence, five potential glycosylation sites, and three internal repeats. Northern-blot analysis showed a single transcript of 0.95 kb. The gene encoding PDI (pdi) was expressed early in development with little transcript remaining following aggregation. The appearance of pdi transcript was inhibited by cAMP, but when cAMP was removed the transcript appeared within 30 min. When cAMP was applied to cells containing pdi mRNA, the transcript disappeared with a half-life of less than 30 min.

Organization and function of a dioxin-responsive enhancer

The dioxin-responsive enhancer upstream of the CYP1A1 gene contains four copies of the recognition motif for the liganded Ah receptor. The results of deletion analyses, linker-scanning analyses, and the analysis of individual enhancer subdomains reveal that each copy of the motif contributes to the response of the enhancer to 2,3,7,8-tetrachlorodibenzo-p-dioxin. In the context of the dioxin-responsive enhancer, a GC box, representing the DNA binding site for Sp1 (or a related transcription factor), has no detectable intrinsic activity but enhances gene expression when linked to a recognition motif for the liganded Ah receptor, thereby producing a synergistic effect on enhancer function.

Retinitis pigmentosa associated with glaucoma--clinical analysis

A clinical analysis of Retinitis Pigmentosa (RP) was made in 2,789 eyes of 1,400 patients seen over a 5 year period (1983-1987), 64 eyes of 32 cases (2.3%) of RP associated with glaucoma were investigated. Of these 32 cases, the angle closure glaucoma was much more than the open angle glaucoma (30/2). More than half of the 32 cases were without cupping of disk, 5 cases did not have the glaucomatous damage to disk in spite of persistent elevated intraocular pressure for 0.5-5 yrs under the maximum medical therapy. 31 cases (97%) had subnormal blood pressure compared with the normal blood pressure value in different age groups. Histopathologic changes of the trabecular meshwork (TM) of 14 eyes showed a little bit more pigment cells in the TM than normal subjects, no typical features that would obstruct the outflow channels.

The proportion of various types of congenital color vision defects

One hundred and three color vision defective subjects were screened from 3456 middle school students with pseudoisochromatic plate test. One hundred subjects out of them were further examined with a test battery including Panel D-15 and FM 100-hue test and Neitz anomaloscope test. It was found that there were 21 protanopes (P), 3 extremely protanomalous (EPA), 13 protanomalous (PA), 25 deutenopes (D), 5 extremely deuteranomalous (EDA), 28 deuteranomalous (DA), 6 unclassified subjects in our investigation. The proportion of various types of congenital color vision defects was P:EPA:PA:D:EDA:DA = 1.00:0.14:0.62:1.19:0.24:1.33.

[Study on change in zinc concentration for diabetic cataractous lenses in rats by means of XIXA]

The SD rats were injected with streptozotocin to induce diabetic cataract. Element Zn as well as K, Ca, Mn, Fe, Cu, Pb, Se, etc. in the eye lenses was determined by means of X-ray induced X-fluorescence analysis (XIXA). Compared to values for normal healthy rats, the concentration of Zn and Fe in the cataractous lenses increased, the concentration of K decreased, and that of the others did not change prominently. The change in Zn concentration was probably to meet the needs of the metabolic adjustment in the eye lenses, which would not be the reason for directly inducing diabetic cataract.

Clinical application of microcomputer to visual function examination

Microcomputer technique is put into use in ophthalmological clinical visual function examination. In visual EOG, ENG, visual tracking, contrast sensitivity and VEP examination, objectifying and standardization of experiment and data analysis are achieved by computer technique. In addition, a lot of manpower and time is saved, test results are obtained faster and more accurately. The basic rational of computerization in clinical visual function examination is presented.

ERG characteristics of congenital stationary night blindness

The ERGs of 9 cases (18 eyes) of congenital stationary night blindness with normal fundi or myopia were tested. All eyes showed nonrecordable rod ERG and cone ERG with normal a-wave. Scotopic mixed ERGs were of the negative type in 7 eyes and of the subnormal type in 11 eyes. The b/a ratio was reduced in all eyes. The ERG characteristics are useful for the classification, estimation of the probable location of the lesion, and differential diagnosis of the disease.