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Biomedical subjects

E Wong

Publications and source records attributed to E Wong.

At least 235 records · Page 13Linked to original sources
PubMed1983

Identification of human sperm antigens to antisperm antibodies.

We have successfully applied SDS (sodium dodecyl sulfate) gel/protein blot radioimmunobinding method to identify the molecular size of sperm antigens that elicit antisperm antibodies from patients with unexplained infertility. Following the transfer of renatured proteins from SDS gel of human sperm extract onto nitrocellulose strips, the radioimmunobinding was performed by incubating the strips with patients' sera at 1:100 dilution and then with I125-labeled goat antihuman immunoglobulin G (IgG) or protein A as detecting probes. Unique sperm antigens that reacted with some patients' sera were identified following the autoradiography of the incubated paper strips. Among the fifty-nine standard serum samples from the Reference Bank of the World Health Organization, about one-fourth of them were found to react predominantly with a sperm protein band having the reference value (Rf value) of 0.2 and the approximate molecular weight of 90,000 dalton. A similar analysis was also performed with serum samples from vasectomized patients. Some of them also revealed a specific binding with the sperm antigen(s) of similar molecular weight. The results of this analysis were also compared with those of conventional tests for sperm antibodies as well as those of microplate radioimmunoassays and enzyme-linked immunoassays. This study suggests that SDS gel/protein blot radioimmunobinding method can be a useful tool for the molecular identification of unique human sperm antigen(s) that elicit naturally occurring antisperm antibodies in patients with unexplained infertility.

Antibodies↗
PubMed1983

Portable Shine-Dalgarno regions; nucleotides between the Shine-Dalgarno sequence and the start codon affect the translation efficiency.

This chapter describes a gene expression system of E. coli that contains a portable Shine-Dalgarno region. Transcription of this system is directed by a hybrid promoter derived from trp and lac-UV5 promoter sequences, which is followed by a region that encodes the portable Shine-Dalgarno region. We used a series of synthetic portable Shine-Dalgarno regions to vary the length (from 4 to 13 bases) of the Shine-Dalgarno by increasing the number of bases on the mRNA that are complementary to the 3' end of 16s rRNA. Increase in the Shine-Dalgarno region to 8 or 13 bases decreased the translation efficiency of the chimeric leukocyte interferon messenger by 40%. In another series of portable Shine-Dalgarno regions, we varied the four bases that follow the Shine-Dalgarno region. The presence of four A residues or four T residues in this region resulted in the highest translation efficiency. The presence of four C residues reduced translation efficiency by 50%, compared with A or T residues. The presence of four G residues after the Shine-Dalgarno region lowered translation efficiency by 75%, compared with A or T residues.

Cloning, Molecular↗
PubMed1983

A hybrid promoter and portable Shine-Dalgarno regions of Escherichia coli.

A gene expression system of Escherichia coli is described here that contains a portable Shine-Dalgarno region. Transcription of this system is under the direction of a hybrid promoter derived from trp and lac-UV5 promoter sequences which is followed by a region that encodes the portable Shine-Dalgarno (PSD) region. Using a series of synthetic PSD regions we varied the length (from 4 to 13 bases) of the Shine-Dalgarno region by increasing the number of bases on the mRNA that are complementary to the 3'-end of 16S rRNA. We found that increase of the Shine-Dalgarno region to 8 or 13 bases decreases the translation efficiency of the chimaeric leucocyte interferon messenger by 40%. We also varied in another series of PSD regions the four bases that follow the Shine-Dalgarno region. We found that the presence of four A residues or four T residues in this region results in the highest translation efficiency. The presence of four C residues reduces the translation efficiency by 50% as compared with PSD regions with A or T residues. The presence of four G residues following the Shine-Dalgarno region lowers the translation efficiency by 75% with respect to PSD regions with A or T residues.

Base Sequence↗
PubMed1982

A new perceptual context-superiority effect: line segments are more visible against a figure than against a ground.

Context, specifically the perceived figure or ground of an ambiguous form that surrounds a diagonal line segment, can influence the discrimination of that line segment even though the physical attributes of the context remain the same during figure-ground reversals. When the line segment was flashed on a region of the form seen as figure, discrimination was twice as accurate as when the line segment was flashed in isolation, and it was at least three times as accurate as when the line segment was flashed on that same region seen as ground.

Discrimination, Psychological↗
PubMed1982

Further studies stereospecificity at carbon 6 for membrane transport of tetrahydrofolates. Diastereoisomers of 5-methyltetrahydrofolates as competitive inhibitors of transport of methotrexate in L1210 cells.

The unnatural d diastereoisomer at carbon 6 of 5-methyltetrahydrofolate was only slightly less effective than the natural 1 diastereoisomer as a competitive inhibitor of the carrier-mediated membrane transport of [3H]methotrexate into L1210 murine leukemia cells. The apparent Ki for a mixture containing equal amounts of both natural and unnatural diastereoisomers was not significantly different from that found for the unnatural form. These results show that the reduced folate carrier system in these cells has a strong affinity for the unnatural stereoisomer, a finding in contrast to that obtained with the corresponding diastereoisomer of 5-formyltetrahydrofolate.

Animals↗
PubMed1982

Molecular mechanism of extinction of liver-specific functions in mouse hepatoma x rat fibroblast hybrids: extinction of the albumin gene.

Hybrids formed by the fusion of mouse hepatoma (BWTG3) and rat fibroblast (JF1) cells exhibit the extinction of mouse albumin and alpha-fetoprotein synthesis. Karyotype analyses suggest that all parental chromosomes are present in the hybrids. The extinction, therefore, of mouse hepatocyte genes is attributed to the inhibitory action of the rat genome. In these studies, we show that these hybrids possess and express the mouse beta-glucuronidase gene (which is encoded on the same chromosome as the mouse albumin and alpha-fetoprotein gene), and we present data of Southern blot analysis which demonstrate that such hybrids have indeed retained both mouse and rat albumin DNA sequences. In addition, using mouse albumin cDNA, we have shown by cDNA-RNA reassociation kinetics that albumin mRNA is virtually absent in these hybrids. We conclude from these studies that the extinction of albumin synthesis involves a mechanism which results in the loss of cytoplasmic albumin mRNA.

Albumins↗
PubMed1982

Is perceived motion a stimulus for smooth pursuit.

Previous investigations have challenged the generality of the claim that perceived motion in an effective stimulus for smooth pursuit eye movements. The experiments extend the scope of these investigations. Three experiments test the hypothesis that perceived motion can serve as the stimulus for pursuit when the eye movement does not generate constraining retinal error information. Observers viewed retinally stabilized displays that elicited the perception that a stationary target was moving or that a moving target was moving faster than it was actually moving. The results failed to confirm the hypothesis. Relevant literature is reviewed. We conclude that perceived movement can act as a stimulus for pursuit only when the "perceptual target" has no retinal counterpart.

Eye Movements↗
PubMed1982

The chloroacetate esterase reaction for mast cells in dermatopathology: a comparison with metachromatic staining methods.

This paper compares standard metachromatic methods with Leder's chloroacetate esterase reaction on mast cells in paraffin wax-embedded tissue of urticaria pigmentosa and a variety of inflammatory and benign neoplastic cutaneous conditions. Our conclusions are that Leder's method allows easier identification of mast cells and can be a useful adjunct to conventional metachromatic methods. The technique could be conveniently adopted in routine dermatopathology for mast cell identification.

Carboxylic Ester Hydrolases↗
PubMed1981

Saccadic programming and perceived location.

The retinal location of a saccadic target was made discrepant with its perceived position by means of an induced displacement. If localizing the target required information stored in memory, the eye was directed to the perceived target position. Otherwise, it was directed to its retinal location. These findings do not conform to either a strictly retinotopic or spatiotopic model of oculomotor control. Rather they suggest that the position information used to program saccades may be either perceptual or retinal/spatial depending upon whether the information must be accessed from memory.

Eye Movements↗
PubMed1981

Zoon's balanitis (balanitis circumscripta plasmacellularis).

The clinical and histopathological features of nineteen cases of Zoon's balanitis and a comparable lesion of the vulva have been reviewed. The condition is particularly distinguished by characteristic histological changes affecting the epidermis and the dermal vasculature. The presence of a plasma cell infiltrate is relatively non-specific. Recognition of these features should allow simple differentiation from premalignant, infective and other inflammatory penile lesions which may be more responsive to treatment.

Adult↗
PubMed1980

GABA receptors in bovine cerebral blood vessels: binding studies with [3H]muscimol.

[3H]Muscimol, a potent GABA agonist used to label GABA receptor sites in brain and invertebrate striated muscle, was found to bind specifically to sites in a crude membrane fraction prepared from bovine cerebral blood vessels. Specific [3H]muscimol binding was saturable of high affinity (Kd = 41 nM), and was selectively inhibited by GABA, specific GABA agonists, and the antagonist bicuculline with potencies similar to what has been found for GABA receptors in mammalian brain. GABA and several GABA agonists including muscimol have been reported to dilate isolated cerebral arteries, but not peripheral blood vessels. The pharmacology of the [3H]muscimol binding site correlated well with that of the vasodilatory response. No significant specific [3H]muscimol binding was detected in aorta and mesenteric arteries. The characteristics of the cerebrovascular muscimol binding site thus are indicative of a physiologically relevant GABA receptor associated with cerebral blood vessels. These findings suggest a direct role for GABA in cerebral vascular function.

Animals↗
PubMed1980

Blindness following frontal sinus irrigation. Report of a case.

Visual loss is a rare and dreaded complication of surgical procedures of the paranasal sinuses. A case of sudden unilateral blindness following irrigation of the frontal sinus is presented and the presumptive pathophysiology is discussed. An awareness of this potential complication as well as early diagnosis with prompt medical and surgical management are essential.

Blindness↗
PubMed1979

A possible neuronal release of [14C] GABA from the rat cerebellum in vivo.

Release patterns for exogenously applied [14C] labelled alpha-amino-n-butyric-acid (GABA) have been investigated in rat cerebellar cortex in vivo. An increase in [14C] GABA release could be evoked by stimulating with high (40 mM) K+ or veratridine (10(-4)M) but not with direct electrical stimulation. Biphasic patterns for high K+ and possibly veratridine stimulated release of GABA suggest the existence of two separate anatomical sources of isotope which are sensitive to these depolarising stimuli. Both K+ and veratridine-evoked GABA release are calcium dependent. Studies involving partial replacement of Na+ with HEPES, (N-2-hydroxyethyl-piperazine-N-2-ethane-sulphonic acid), sucrose or choline chloride also reveal a sodium dependency of [14C] GABA release. These studies collectively indicate a neuronal source for evoked GABA release, a criterion for transmitter identification not previously satisfied in the cerebellar cortex.

Animals↗