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Biomedical subjects

W Jiang

Publications and source records attributed to W Jiang.

At least 307 records · Page 17Linked to original sources
PubMed1994

Effects of designer drugs on the chicken embryo and 1-day-old chicken.

The present study was conducted to examine the effects of d-amphetamine and the designer drugs 3,4-methylenedioxymethamphetamine (MDMA), N-methyl-3,4-methylenedioxyphenyl-3-butamine (HMDMA), 3,4-methylenedioxyphenyl-2-butanamine (BDB), 3,4-methylenedioxyphenyl-1-ethanamine (MDM1EA) in the chick embryo and the young chicken. HMDMA and MDM1EA had no effect on motility on day 14 of embryogenesis, while MDMA, BDB, and d-amphetamine decreased embryonic motility at one or more doses. On day 1 posthatch, chickens were challenged with cumulative injections of water or the same drug that they had received in ova. With the exception of MDM1EA, all of the drugs produced effects such as distress vocalization, wing extension, tremor, flat body posture, bursting forward movements, loss of righting reflex, and convulsant-like kicking. Pretreatment with drug in ova resulted in tolerance to certain drug effects and supersensitivity to other drug effects. Furthermore, BDB significantly decreased hatchability, MDM1EA decreased body weight, and HMDMA decreased liver weight. Further studies are needed to determine the mechanism(s) of toxicity in this species.

3,4-Methylenedioxyamphetamine↗
PubMed1994

Behavioral and developmental effects of two 3,4-methylenedioxymethamphetamine (MDMA) derivatives.

The effects of 3,4-methylenedioxymethamphetamine (MDMA or 'ecstacy') and two structurally related compounds, N-methyl-1-(3,4-methylenedioxyphenyl)-1-ethanamine (MDM1EA) and N-methyl-1-(3,4-methylenedioxyphenyl)-3-butanamine (HMDMA) were examined in two preparations: (i) a drug discrimination procedure in MDMA-trained rats and (ii) the chicken embryo, for determination of the direct effects of these compounds on the developing organism. The highest doses of MDM1EA and HMDMA partially substituted for MDMA, whereas higher (30-60 mg/kg) doses of HMDMA evoked clonic seizures in a separate group of rats. In chicken embryos MDMA had no effect on body, brain or liver weight, while the highest dose of MDM1EA decreased body weight and the 2 lowest doses of HMDMA increased body weight. All doses of HMDMA decreased liver weight (expressed as % body weight) when compared with contemporaneous water-treated controls. Taken together, the results of these experiments suggest that structurally related compounds share some stimulus properties with MDMA and may therefore share abuse liability. Furthermore, both MDMA-related compounds produced adverse effects on the developing organism, whereas MDMA did not.

3,4-Methylenedioxyamphetamine↗
PubMed1994

Suppression of mitogenic activity by stable expression of the regulatory domain of PKC beta.

The amino-terminal regulatory domain portion of each protein kinase C (PKC) family member (which in the case of PKC beta 1 includes the pseudosubstrate, C1, V1 and C2 domains) plays an important role in regulating the kinase activity of the carboxyl-terminal catalytic domain. To examine the possibility that this regulatory domain region (designated 'PAT') might have biological functions independent of the catalytic domain, we have developed derivatives of R6 cells which stably express a truncated PKC beta 1 cDNA that encodes the amino-terminal 317 amino acids, including the entire regulatory domain. These R6-plPAT cells express abundant amounts of a 38 kDa protein which binds a labeled phorbol ester, but lacks protein kinase activity. In contrast to the 79 kDa PKC beta 1 holoenzyme which, when overexpressed in R6 cells, is found mostly in the cytosol, the 38 kDa PAT protein is predominantly associated with the particulate subcellular fraction. Furthermore, the PAT protein fails to show down-regulation following treatment of R6-plPAT cells with 12-O-tetradecanoylphorbol-13-acetate (TPA). Evidence is also presented that TPA-stimulated growth is suppressed in R6-plPAT cells. These findings suggest that the PKC beta 1 regulatory domain could be involved in the suppression of mitogenic signaling.

Animals↗
PubMed1994

Family of the major cold-shock protein, CspA (CS7.4), of Escherichia coli, whose members show a high sequence similarity with the eukaryotic Y-box binding proteins.

The cspA is a gene of Escherichia coli, whose expression is specifically induced at low temperatures to a level of 13% of total protein synthesis. The CspA protein consisting of 70 amino acid residues has high sequence similarity with eukaryotic Y-box DNA-binding proteins. We found two independent clones from the Kohara miniset phage collection, which hybridized with a DNA fragment containing cspA. DNA sequencing of these clones confirmed that the two genes are highly homologous to cspA. One designated cspB is mapped at 35 min on the E. coli chromosome and encodes a 71-residue protein with 79% identity to CspA, while the other, cspC, is mapped at 40 min and encodes a 69-residue protein with 70% identity. In addition, a DNA sequence upstream of the clpA gene at 19 min published elsewhere contains an open reading frame for a 74-residue protein with 45% identity to CspA. All csp genes were fused in the coding regions with the lacZ gene, and the expression of beta-galactosidase was examined for these hybrid genes upon cold shock. A similar cold-shock induction to cspA was observed for cspB but not cspC and cspD. These results indicate that E. coli has a family of the cspA gene, some of which are induced by cold shock.

Amino Acid Sequence↗
PubMed1994

Purification of Borrelia burgdorferi outer surface protein A (OspA) and analysis of antibody binding domains.

The major outer surface protein, OspA, of Borrelia burgdorferi is a lipoprotein which is a particular interest because of its potential as a vaccine candidate. However, serotypic and genetic analysis of OspA from both European and North American strains have demonstrated antigenic and structural heterogeneities. We purified OspA to homogeneity by exploiting its resistance to trypsin digestion. By treating spirochetes with trypsin and then using Triton X-114 extraction and ion-exchange chromatography, we obtained a yield of 2 mg of pure OspA protein per liter of culture. INtrinsic labeling with [14C]palmitic acid confirmed that OspA was lipidated, and partial digestion established lipidation at the amino-terminal end of the molecule. The reactivity of five anti-OspA murine monoclonal antibodies to nine different isolates of B. burgdorferi was ascertained by Western blot (immunoblot) analysis. Purified OspA was fragmented by enzymatic or chemical cleavage, and the monoclonal antibodies were able to define four distinct immunogenic domains. Further resolution of the epitope specificity to determine humoral and cellular immune responses to OspA has implications for vaccine development and for the utility of this protein as a reagent in diagnostic testing for Lyme borreliosis.

Amino Acid Sequence↗
PubMed1994

Corrective responses to loss of ground support during walking. II. Comparison of intact and chronic spinal cats.

1. The preceding study described a corrective response in cats when one hind leg steps into a hole. In this investigation we examine the extent to which this behavior is organized at the spinal level by comparing the responses elicited in intact and chronic spinal cats. 2. Adult cats were trained to step bipedally with their hind legs on a treadmill. After training, the responses to stepping into a hole cut in the treadmill belt were monitored with a video recorder and by recording electromyograms from muscles in both hind legs. The responses to stepping into the hole were also recorded in chronic spinal cats that had recovered the ability to step with their hind legs a few weeks after spinalization. 3. The behavioral responses in the two groups of animals differed in two respects. First, the latency of the onset of the flexion movement to remove the foot from the hole was shorter in intact animals (70-150 ms in intact vs. 130-350 ms in spinal animals). Second, the flexion movement in the intact animals was stronger. The exaggerated flexion movement in intact animals lifted the paw well clear of the hole and allowed support to be regained on the treadmill belt. The weaker flexion movement in spinal animals was usually insufficient to lift the paw completely from the hole. 4. Differences in the motor patterns recorded from flexor muscles during the corrective response in intact and spinal animals correspond with the differences in the kinematics. First, the onset of flexor activity after the foot entered the hole was delayed by approximately 100 ms in spinal animals relative to intact animals. Second, in intact animals the magnitudes of flexor bursts were increased relative to the flexor bursts associated with the swing phase during stepping, whereas in spinal animals flexor bursts during the corrective response resembled those occurring during swing. 5. Similarities in the duration and the timing of bursts in different flexor muscles in intact and spinal animals during the corrective response and during swing indicated that the corrective response involves activation of the spinal system that normally produces swing phase flexor activity. We conclude that activation of this system is facilitated by input from supraspinal structures during the corrective response in intact animals. 6. In all intact animals and three of five spinal animals, support of the hindquarters when the foot entered the hole was maintained by the contralateral leg.(ABSTRACT TRUNCATED AT 400 WORDS)

Afferent Pathways↗
PubMed1994

[The frequency-domain analysis of TEOAE in neonates and youths].

Transiently evoked acoustic emissions (TEOAE) is a rapid, noninvasive and objective audiologic method. It has been used in clinic. In order to observe effects of transient stimulus sounds on TEOAE, TEOAE evoked by click and tone-pip (1kHz, 2kHz) was examined in 18 neonates and 18 youths. The observed TEOAE waveforms were used for frequency-domain analysis. The results revealed that there were no significant differences in TEOAE incidence between the neonates and youths, and among the three kinds of stimuli. The incidence of the click evoked acoustic emission in the neonate group (within 4 days post partum) was 91.7%, it was lower than those reported by other authors. The frequency-domain analysis showed that there were no significant differences of bandwidth among the three kinds of stimuli, but the frequency peak was different according to the different stimulus sounds. It was found that there were somewhat dependence of TEOAE characteristic spectrum on stimulus sound frequency, this might be related to the mechanical tuning property of the inner ear and the resonance of the external and the middle ear.

Acoustic Stimulation↗
PubMed1994

Saturation diving with heliox to 350 meters. Observation on hearing threshold, brainstem evoked response and acoustic impedance.

Four divers were compressed to 350 m to observe changes in hearing threshold, brainstem evoked response and acoustic impedance. The divers experienced no tinnitus, impairment of hearing, earache during compression. Examination showed that the threshold of lower frequency range of hearing was elevated because of the masking effect of the noise in the hyperbaric chamber. Changes in waveform and latency of brainstem evoked response were due to changes in sound wave transmission affected by the chamber pressure and a poor ratio of signal to noise in the hyperbaric environment with heliox. All these changes were transient. After leaving the chamber, the hearing threshold and brainstem evoked response returned to normal. Besides, there were no changes in tympanogram, acoustic compliance and stapedius reflex before and after diving. This indicated the designed speed of compression and decompression in the experiment caused no damage to the divers' acoustic system, and the functions of their Eustachain tubes, middle and inner ears were normal during the diving test.

Acoustic Impedance Tests↗
PubMed1994

[Study on polymorphism of ribosomal RNA gene in Chinese Hans and Yis].

In the secondary constriction region of the short arm of human group D and group G acrocentric chromosomes there are tandemly repeated sequences of transcriptable segments and non-transcriptable spacers of rRNA genes. In the non-transcriptable spacer segments there is a polymorphic region with length variation. This paper reports the results obtained when the BamHI digested products of genomic DNA from 36 cases of Han nationality and those from 40 cases of Yi nationality were probed with a cDNA subprobe, pA(BE), which corresponds to the downstream one third of the 28S rRNA gene and is 1.6kb long with BamHI and EcoRI restriction sites at its two terminal respectively, using Southern blotting and molecular hybridization techniques. A total of 10 different restriction fragments were detected. Four fragments (7.9, 4.9, 4.0 and 1.2 kb) were seen in all subjects tested and the frequencies of six other polymorphic fragments in Hans and Yis (10.0, 9.4, 8.5, 6.7 6.0 and 3.0 kb) showed no significant difference when compared to each other. From the 10 different patterns of combination of restriction fragments four of them (1HY, 2HY, 3HY and 4HY) were detected in both Hans and Yis with no significant difference between their respective frequencies. Four other patterns (5H, 6H, 7H and 8H) were only seen in Hans with individual frequencies not high enough to be statistically significant. However, the statistical test for the combined frequencies of these four patterns showed highly significant difference between Hans and Yis (P < 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)

China↗
PubMed1994

Hearing shift and inner ear pathology of guinea pigs exposed to octave bands of noise centered at 63 Hz and 4 kHz.

Twenty-four guinea pigs with normal Preyer's reflex were exposed to the octave bands of noise centered at 63 Hz and 4 kHz, 110 dB SPL. The duration of exposure was 4 and 8 hours respectively. The permanent shift of the guinea pigs at the above two frequencies was at 4-8 kHz. As the duration of exposure were 4 hours, the threshold shift at 63 Hz was smaller than that at 4 kHz. But as the duration of exposure was 8 hours, the threshold shift at 63 Hz and 4 kHz was almost the same. No morphological change of the inner ear was observed in the guinea pigs exposed for 4 hours at the octave bands of noise centered at 63 Hz and 4 kHz, but ultrastructural abnormalities were noted. After the animals were exposed for 8 hours, morphological, ultrastructural changes in the inner ear were observed. The main pathologic changes were seen at the second turn of the cochlea. These changes in hearing physiology and pathology suggest that a high intensive low frequency noise can result in high frequency hearing loss and that the use of A-weighted levels of specific damage risk criteria for noise sources may be inappropriate.

Animals↗
PubMed1993

Cloning of the PABA peptide hydrolase alpha subunit (PPH alpha) from human small intestine and its expression in COS-1 cells.

PABA peptide hydrolase (PPH) from human enterocytes is comprised of two subunits, alpha and beta. PPH alpha is over 70% identical to meprin, a protease isolated from mouse and rat kidney. The enzyme shows a modular organization in that it contains an astacin protease domain, an adhesive domain, an EGF-like domain, an a putative C-terminal membrane spanning domain. Expression of a chimeric meprin-PPH alpha cDNA in COS-1 cells led to the synthesis of immature, transport-incompetent homodimers. In addition, complex glycosylated forms were detected in the culture medium, suggesting that the enzyme is secreted after proteolytic removal of the membrane anchor.

Amino Acid Sequence↗
PubMed1993

Amplification and overexpression of cyclin D1 in human hepatocellular carcinoma.

Amplification of the chromosome 11q13 region occurs in several types of human cancer including esophageal, breast, lung, bladder and hepatocellular carcinoma (HCC). The gene cyclin D1 maps to this region in close proximity to two proto-oncogenes hst-1 and int-2. We previously demonstrated that cyclin D1 was not only amplified but also overexpressed in about 30% of human esophageal cancers. To investigate the role of cyclin D1 in human hepatocellular carcinoma (HCC), DNA from 30 HCC and 5 control liver tissues from Taiwan and also the HCC cells lines HepG2 and Hep3B, were examined for amplification of the cyclin D1 gene. A 3 to 20-fold amplification was found in 4 of the 30 (13%) HCC samples but not in any of the 5 control tissues or the 2 cell lines. Immunohistochemical analysis of cyclin D1 indicated overexpression of this protein in tumors that displayed gene amplification. Weak or negative staining was observed in the other HCC samples as well as in the control tissues and cell lines. These data suggest that increased expression of cyclin D1 may play an important role in the development of a subset of human HCC, perhaps by perturbing normal control of the cell cycle.

Blotting, Northern↗
PubMed1993

Cloning, expression, and chromosomal localization of the mouse meprin beta subunit.

Meprins are plasma membrane homo- or hetero-oligomeric metalloendopeptidases that contain glycosylated alpha and/or beta subunits. This paper reports the cloning and sequencing of the mouse kidney beta subunit. The primary translation product is composed of 704 amino acids which includes a transient signal sequence of 20 amino acids at the NH2 terminus. The protease domain (Asn-63 to Leu-260) contains the putative zinc-binding motif characteristic of metalloendopeptidases of the "astacin family." The COOH terminus contains an epidermal growth factor-like domain, a potential membrane-spanning domain, and an additional 26 amino acids. The beta subunit has an overall 42% identity to the alpha subunit, however, a 56-amino acid segment near the COOH terminus of alpha is missing in beta, and the putative transmembrane and cytoplasmic domains of the subunits share no significant sequence similarity. NH2-terminal analyses of detergent-solubilized mature forms revealed that, unlike alpha, the prosequence (Leu-21 to Lys-62) is not removed from the beta subunit. Northern blot analysis revealed a 2.5-kilobase message for the beta subunit in the kidney and intestine of C57BL/6 and C3H/He mice. The gene for the beta subunit was localized to mouse chromosome 18. These studies indicate that alpha and beta probably derived from a common ancestral gene, but have evolved so that their genes are on two different chromosomes, and their tissue-specific expression and post-translational processing differ.

Amino Acid Sequence↗
PubMed1993

Altered expression of the cyclin D1 and retinoblastoma genes in human esophageal cancer.

We have examined DNA from four human esophageal carcinoma cell lines and 50 primary esophageal carcinomas obtained from China, Italy, and France for amplification of the cyclin D1 gene. We also examined 36 of these 50 carcinomas for expression of the cyclin D1 and retinoblastoma (RB) proteins by immunohistochemistry. We found a 3- to 10-fold amplification of the cyclin D1 gene in 16 of the 50 (32%) tumors and in two of the four cell lines. Cyclin D1 protein was overexpressed in 12 of 13 tumors and the two cell lines that showed gene amplification when compared to normal controls. Studies on RB protein expression indicated that 6 of the 36 (17%) tumor samples examined and one cell line did not show detectable expression of this protein. The tumors and cell lines that had cyclin D1 gene amplification and overexpression exhibited normal levels of expression of RB protein. By contrast, the tumors and cell line that did not appear to express the RB protein did not show amplification of the cyclin D1 gene and expressed only low levels of the cyclin D1 protein (P = 0.03). These results suggest that the inhibitory effect of RB on cell cycle progression can be abrogated during tumor development either by loss of expression of the RB gene or by increased expression of the cyclin D1 gene.

Blotting, Southern↗
PubMed1993

Relation of cardiovascular responses to mental stress and cardiac vagal activity in coronary artery disease.

Forty-six patients with documented coronary artery disease were studied to examine the relation of cardiovascular reactivity to mental stress and cardiac vagal activity. Cardiac vagal activity was measured by means of frequency-domain analysis of heart rate variability with 48-hour out-of-hospital Holter monitoring. The amplitude of the high-frequency component (0.16 to 0.40 Hz) of heart rate variability is considered to be an index of cardiac vagal activity. Cardiovascular reactivity was measured in the laboratory during a 3-minute public speaking task. Results revealed that (1) the amplitude of the high-frequency component was significantly higher during sleep (24.6 +/- 11.3 ms) than during waking (18.2 +/- 8.0 ms) (p = 0.002); (2) compared to subjects with low diastolic blood pressure reactivity, those who displayed high diastolic blood pressure reactivity exhibited a significantly lower amplitude of the high-frequency component (19.2 +/- 6.9 vs 23.4 +/- 9.6 ms, p = 0.03). These results indicate that decreased cardiac vagal activity may contribute to the exaggerated diastolic blood pressure reactivity to mental stress in patients with coronary artery disease.

Aged↗