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Biomedical subjects

T Huang

Publications and source records attributed to T Huang.

At least 145 records · Page 8Linked to original sources
PubMed1994

Mapping of herpes simplex virus 1 genes with mutations which overcome host restrictions to infection.

Earlier studies have shown that the thymidine kinase-negative baby hamster kidney (BHKTK-) cell lines expressing constitutively the herpes simplex virus 1 (HSV-1) glycoprotein D (gD), designated BJ, restrict infection by HSV-1 at the level of virus entry. U10, a HSV-1 mutant not restricted by the BJ cells, carried the substitution of proline for Leu25 in the gD gene, suggesting that gD encodes a specialized domain which precludes virus entry into cells expressing gD. Analyses of a new series of 36 unrestricted viral mutants showed the following. (i) Only two mutants contained mutations at a site which did not overlap with the previously reported mutation. A representative of a previously mapped mutant and one of the two new mutants were examined in detail. Thus, in the gD of mutant U30 Ala185 was replaced by threonine, whereas in gD of U21, Ala185 and Leu25 were replaced with threonine and proline, respectively. U30 and U21 multiplied better than the wild-type parent virus in the parental BHKTK- cells. (ii) Transfer of the gD gene from U21 or U30 to wild-type parent virus or to the gD- virus FgD beta yielded recombinants which, while capable of infecting BJ cells, were considerably less efficient than the parent unrestricted mutants, suggesting that the latter contained additional mutations which were responsible in part for the unrestricted phenotype. Conversely, marker rescue of mutant viruses with wild-type gD reduced but did not abrogate entirely the unrestricted phenotype. (iii) Mutations in gD which conferred the unrestricted phenotype were not random. (iv) gD plays a role in the restriction, inasmuch as preincubation of cells expressing gD with antibodies to gD abolished restriction. (v) In mutant R5000, the gD substitution Ser140 to Asn was capable of overcoming a restriction of a BHKTK- clonal line which does not express gD but conferred very low ability to replicate on BJ cells. We conclude that (a) uncloned stocks of BHKTK- cells exhibit a low level restriction to infection with wild-type virus, (b) clonal lines of BHKTK- cells which vary with respect to the stringency of restriction express either allelic genes differing in the properties of their products or products of different genes, and (c) both the restricted and unrestricted phenotypes reflect the interactions of gD with these cellular products. The implications of these conclusions with respect to the restriction imposed on BHK cells by the expression of gD are discussed.

Animals↗
PubMed1994

A comparative study of the properties between human fibronectin isolated from placenta of early and term pregnancy.

Fibronectin from human early pregnancy (5-8 weeks) placenta (epFN) has been isolated by 2M urea-PBS extraction and purified by heparin-Sepharose 4B affinity chromatography followed by Sepharose CL-6B gel filtration, and compared with that of term placenta (tpFN). According to the analysis on SDS-polyacrylamide gel electrophoresis (SDS-PAGE) and Western-blots, epFN was similar to tpFN; both are composed of two 250 KD subunits, larger than 220 KD subunits of plasma fibronectin (pFN). They reacted with antibodies against pFN and monoclonal antibodies (mAbs) raised against three mainly functional domains of amniotic fluid fibronectin (amFN), respectively. However, the affinity of epFN with mAb against heparin-binding domain was stronger than that with mAb against gelatin-binding domain; this phenomenon could not be observed with tpFN and pFN. The results of lectin-binding capacity indicated that epFN was not only distinct from pFN but also from tpFN on its carbohydrate composition. We also found there were much more FN-binding proteins in early placenta than in term placenta. The significance of these results are discussed.

Adhesins, Bacterial↗
PubMed1994

Sequence variation in the circumsporozoite protein gene of Plasmodium vivax appears to be regionally biased.

We have sequenced the circumsporozoite protein gene from 16 isolates from China, the Philippines, Papua New Guinea and the Solomon Islands. We found very limited polymorphisms in the non-repetitive regions of the circumsporozoite gene from these isolates. All samples from China contained a 36-base insert 3' to the repeats previously seen only in a North Korean isolate. Limited variation was found in the repeat regions, which allowed these and previously sequenced isolates to be classified into groups based on repeat structure. These groupings also correlate with the geographical origin of the isolates.

Amino Acid Sequence↗
PubMed1994

Clinical observation of treatment of hypertension with calcium.

The effect of oral calcium supplementation (1000 mg/day) on hypertension was studied in 57 borderline and mild-to-moderate hypertensive patients in a randomized, double-blind, placebo-controlled study for 14 weeks. Twenty-five patients from the above groups (11 from the calcium-treated group and 14 from the placebo group) were studied in a crossover fashion for 14 more weeks. The high calcium intake lowered systolic blood pressure by 17 mm Hg (P < .01), and diastolic blood pressure by 11 mm Hg (P < .01). Fifty percent of the calcium-treated patients showed a significant antihypertensive effect and were termed calcium responders. In the crossover study, serum sodium was lower after taking calcium than after placebo intake (P < .05). Pretreatment plasma free calcium content of the calcium-responsive patients was significantly lower (P < .05) than in the calcium nonresponsive patients, and was highly significantly increased (P < .01) after administering calcium. The result showed that oral calcium supplementation can lower blood pressure in a significant fraction of essential hypertensive subjects, and that the free calcium level in plasma may help identify calcium-responsive individuals. While the mechanism by which increased calcium intake lowers blood pressure in hypertension is still undetermined, these data support an underlying relationship between hypertension and calcium and possibly sodium metabolism.

Administration, Oral↗
PubMed1994

The UL21 gene products of herpes simplex virus 1 are dispensable for growth in cultured cells.

A viral deletion mutant (delta UL21) that lacked the sequences encoding 484 of the predicted first 535 amino acids of the UL21 open reading frame was genetically engineered and studied with respect to its phenotype in cells in culture. We report the following. (i) The replication of delta UL21 was identical to that of the parent herpes simplex virus 1 (HSV-1) strain F in Vero cells, but the yields were three- to fivefold lower than those of the parent virus in human embryonic lung cells. (ii) To characterize the UL21 protein, we immunized rabbits against a purified bacterial fusion protein consisting of glutathione S-transferase fused to the majority of the coding domain of the UL21 gene. Rabbit antiserum directed against the fusion protein recognized a broad band with an apparent M(r) of 62,000 to 64,000 in lysates of cells infected with HSV-1 strain F and in virions purified from the infected cell cytoplasm. This band was absent from lysates of mock-infected cells or cells infected with the delta UL21 virus. The band was significantly reduced in intensity in lysates of cells infected in the presence of phosphonoacetic acid, indicating that it is expressed as a late (gamma 1) gene. (iii) Immunofluorescence studies localized the UL21 antigen primarily in brightly staining granules in the cytoplasms of infected cells. Taken together, the data indicate that the UL21 protein is a virion component dispensable for all aspects of replication of HSV-1 in the cells tested. The electrophoretic mobility of the UL21 protein suggests that it is extensively modified posttranslationally.

Amino Acid Sequence↗
PubMed1994

[DNA sequencing of circumsporozoite protein genes of Plasmodium vivax from four different countries in west Pacific region: comparative study on the flank sequences].

P. vivax CSP gene of 18 isolates from infected blood of patients living in China, Philippines, Solomon Islands and Papua New Guinea in West Pacific region has been sequenced from both terminal end. The total readable sequence in most isolates was about 725 base pair (bp), including the first two repeat units (70-330 bp) to the N terminus, and the last two repeat units to the C terminus (763-1,228 bp). Comparison and analysis of these obtained sequences with the published sequences of N.K., Thai., Belem, Sal-l. and BZL strains showed that:the N and C terminus sequences flanking the centre repeats in CSP gene were highly conserved in all isolates and identical with the 5 published sequences but a double base pair substitution in each end and a remarkable polymorphism in the postrepeat variable region in C terminus were found, including some diversities with obvious geographic characteristics which have not been reported previously.

Animals↗
PubMed1994

Treatment of gender dysphoria (transsexualism).

Gender dysphoria, or transsexualism, is a condition involving incongruity between an individual's anatomic sex and personal sense of gender identity. Only in the last 15 years have Standards of Care been established and a professional organization developed to bring definition and consistency to the field (Harry Benjamin International Gender Dysphoria Association). A typical course of treatment lasts several years and includes psychological/psychiatric evaluations, completion of the "real life" test, administration of hormone therapy to create desired secondary sex characteristics, and finally sex reassignment surgery. As the field has developed and health-care professionals and the public have become more aware, increasing numbers of individuals are coming forward to seek evaluation and treatment. Published follow-up studies documenting long-term outcome are needed now. Current intervention techniques have progressed beyond the "experimental" stage and can be regarded as accepted medical practice.

Combined Modality Therapy↗
PubMed1993

Spontaneous otoacoustic emissions: measurement and data.

Sounds from the ear canal were measured and then analyzed off-line. A peak-picking algorithm located spectral maxima which might be designated as spontaneous otoacoustic emissions (SOAEs). The output from a 0.5-cc syringe, used to stimulate the volume of the ear canal, was also measured, analyzed and used to approximate the false-alarm rate of the measurement system. SOAE prevalence estimates depended on the false-alarm rate, just as the hit rate in a yes-no task does. With a false-alarm rate of zero, trends that have been found to be significant in the pooled results of other surveys were replicated: more SOAEs in the right ear, more SOAEs in females, and increased probability that the contralateral ear has an SOAE if the ipsilateral ear has an SOAE. In addition, many SOAEs failed to be detected in consecutive spectral analyses because they fluctuated in level.

Acoustic Stimulation↗
PubMed1993

Metrazole induces the sequential activation of c-fos, proenkephalin, and tyrosine hydroxylase gene expression in the rat adrenal gland: modulation by glucocorticoid and adrenocorticotropic hormone.

The immediate-early gene c-fos (a nuclear transcription factor) has been viewed as a nuclear "third messenger" or cellular "master switch." Both in vitro and in vivo studies have suggested that the proenkephalin (Penk) and tyrosine hydroxylase (TH) genes are potential targets of this immediate-early gene. We investigated the relationships between the activation of the c-fos gene and the activation of the Penk and TH genes in both rat hippocampus and adrenal using a commonly used model, metrazole (MTZ)-induced convulsions. The administration of MTZ produced a sequential elevation in c-fos, preproenkephalin (PPenk), and TH mRNAs. One hour after MTZ administration, c-fos mRNA was increased about 10-fold in rat hippocampus and about 5-fold in rat adrenal, without a significant change in spinal cord levels. Immunocytochemistry revealed that Fos-like immunoreactivity was greatly increased in both hippocampus and adrenal medulla at 3 hr after MTZ administration. The levels of PPenk and TH mRNAs were significantly increased (5-fold and 3-fold, respectively) in the adrenal 6 hr after MTZ treatment. The effects of MTZ on c-fos, PPenk, and TH mRNAs were dose dependent in both adrenal and hippocampus. In the adrenal, both the basal levels and the MTZ induction of PPenk mRNA were significantly attenuated by hypophysectomy (hypox) and were partially reinstated by adrenocorticotropic hormone (ACTH) replacement. In contrast, the basal levels of c-fos and TH mRNAs were not altered in hypox rat adrenal. ACTH treatment completely blocked the MTZ induction of adrenal c-fos mRNA and the subsequent induction of Fos-like immunoreactivity, whereas MTZ increased PPenk and TH mRNAs nearly 3-fold. Thus, in hypox rats MTZ can increase adrenal c-fos and TH mRNA levels without a corresponding increase in PPenk mRNA, whereas in ACTH-treated rats PPenk and TH mRNA levels in adrenal can be increased by MTZ without a preceding increase in c-fos mRNA. The MTZ induction of c-fos appears neither sufficient nor always necessary for the subsequent MTZ induction of Penk and TH gene expression. We conclude that c-fos, Penk, and TH genes can be differentially regulated in the adrenal of hypox rats or animals treated with ACTH, although they are co-localized in the same medullary cells.

Adrenal Glands↗
PubMed1993

Effects of pentoxifylline on sperm motility and hyperactivated motility in vitro: a preliminary report.

Previous reports (2, 3) have suggested that pentoxifylline increases sperm motility. In this preliminary report based on five asthenozoospermic and five normal motility semen samples, we were unable to demonstrate any statistically significant effect of pentoxifylline on percent motility of human spermatozoa. However, in vitro exposure to capacitation medium with pentoxifylline may lead to an increase in total hyperactivated motility in asthenozoospermic samples, an effect not evident in the normal motility samples in this study.

Humans↗
PubMed1993

Mathematic proof of Schachar's hypothesis of accommodation.

To evaluate whether there is increased or decreased zonular tension during accommodation, we developed a qualitative small displacement model using Rayleigh's method to determine the characteristics of the human lens changes that occur during accommodation. We found that the optical power of the human lens increased linearly with zonular tension. Our results definitely prove Schachar's hypothesis of accommodation.

Accommodation, Ocular↗