Biomedical subjects

C H Huang

Publications and source records attributed to C H Huang.

At least 19 recordsLinked to original sources

PubMed1992

Molecular analysis of human glycophorin MiIX gene shows a silent segment transfer and untemplated mutation resulting from gene conversion via sequence repeats.

The human glycophorin (HGp) loci that define the red blood cell surface antigens of the MNSs blood group system exhibit considerable allelic variation. Previous studies have identified gene conversion events involving HGpA(alpha) and HGpB(delta) that produced delta-alpha-delta hybrid genes which differ in the location of breakpoints. This report presents the molecular analysis of HGpMilX, the first example of a reverse alpha-delta-alpha hybrid gene that specifies a newly described phenotype of the Miltenberger complex. A novel restriction fragment unique to the HGpMilX gene was detected by Southern blot hybridization. The structure of the genomic region encoding the entire extracellular domain of the MilX protein was determined. Nucleotide sequencing of amplified genomic DNA showed that a silent segment of the HGpB(delta) gene had been transposed to replace the internal part of exon III in the HGpA(alpha) gene, thereby resulting in the formation of the MilX allele with an alpha-delta-alpha configuration. The proximal alpha-delta breakpoint was found to be flanked by a direct repeat of the acceptor splice site, whereas the distal delta-alpha breakpoint was localized to a palindromic region. This DNA rearrangement, with a minimal transfer of 16 templated nucleotides and a single mutation of untemplated adenyl nucleotide, not only created two intraexon hybrid junctions but transactivated the expression of a new stretch of amino acid residues in the MilX protein. Such a segment replacement may have occurred through the directional transfer from one duplex to the other via the mechanism of gene conversion. The occurrence of HGpMilX as another hybrid derived from parts of parent genes underlines the role of the recombinational "hotspot" in the generation of allelic diversity in the glycophorin family.

Amino Acid Sequence↗

PubMed1992

Molecular basis for the human erythrocyte glycophorin specifying the Miltenberger class I (MiI) phenotype.

Human glycophorin Mil (HGpMil) is a structural variant of the MNSs blood group system that specifies the Miltenberger class I phenotype. We report here the molecular basis of the HGpMil gene identified in a white family in which the first homozygote was encountered. Immunoblotting analysis showed the expression of HGpMil and HGpB but the absence of HGpA on the homozygous Mil erythrocytes. Southern blot analysis detected no gross alterations in gene structure or band intensity. Genomic sequences encompassing exons II and III of the HGpMil gene were amplified by single-copy polymerase chain reaction. Restriction digestion and direct DNA sequence analysis showed that HGpMil gene is derived from an alpha N allele of HGpA and differs from the latter in the third exon by a single nucleotide change. In HGpMil, the presence of a deoxythymidine at the second position of codon 28 (ATG) not only resulted in a methionine substitution but also altered the consensus sequence for N-glycosylation from Asn-Asp-Thr to Asn-Asp-Met. These data are consistent with the occurrence of Mil on the red blood cell membrane as a variant deficient in the asparagine-linked carbohydrate unit. Significantly, this particular point mutation lies in between the two half-sites of a direct repeat that has been implicated to facilitate the recombination events leading to several other glycophorin genes of the Miltenberger series. Based on this relatedness, we propose an untemplated nucleotide replacement resulting from a gene conversion event as the molecular basis for the origin of HGpMil gene.

Amino Acid Sequence↗

PubMed1992

Interdigitated bilayer packing motifs: Raman spectroscopic studies of the eutectic phase behavior of the 1-stearoyl-2-caprylphosphatidylcholine/dimyristoylphosphatidylcholine binary mixture.

The thermotropic properties and acyl chain packing characteristics of multilamellar dispersions of binary mixtures of 1-stearoyl-2-caprylphosphatidylcholine (C(18):C(10)PC), an asymmetric chain species, and dimyristoylphosphatidylcholine (C(14):C(14)PC), a symmetric chain lipid, were monitored by vibrational Raman spectroscopy. In order to examine each component of the binary mixture separately, the acyl chains of the symmetric chain species were perdeuterated. As shown by differential scanning calorimetry, the mismatch in the gel phase bilayer thickness between the two lipid components generates a lateral phase separation resulting in two distinct gel phases, G(I) and G(II), which coexist over much of the composition range. The Raman data demonstrate that the mixed interdigitated phase (three chains per headgroup), analogous to single component phase behavior, is retained when the C(18):C(10)PC component act as a host for the G(I) gel phase. In contrast, the C(18):C(10)PC molecules exhibit partial interdigitation (two chains per headgroup) when they are included as guests within the C(14):C(14)PC host matrix to form the G(II) gel phase. Compared to pure C(14):C(14)PC bilayers at equivalent reduced temperatures, the host G(II) gel phase C(14):C(14)PC molecules exhibit an increased acyl chain order, while for the host G(I) gel phase the C(14):C(14)PC lipid species show increased intrachain disorder.

Dimyristoylphosphatidylcholine↗

PubMed1992

Structure and cohesive properties of sphingomyelin/cholesterol bilayers.

Thermal, structural, and cohesive measurements have been obtained for both bovine brain sphingomyelin (BSM) and N-tetracosanoylsphingomyelin (C24-SM) in the presence and absence of cholesterol. A goal of these experiments has been to clarify the mechanisms responsible for the strong interaction between sphingomyelin and cholesterol. Differential scanning calorimetry shows that fully hydrated bilayers of BSM and C24-SM have main endothermic phase transitions at 39 and 46 degrees C, respectively, that reflect the melting of the acyl chains from a gel to a liquid-crystalline phase. For each lipid, the addition of cholesterol monotonically reduces the enthalpy of this transition, so that at equimolar cholesterol the transition enthalpy is zero. The addition of equimolar cholesterol to either BSM or C24-SM coverts the wide-angle X-ray diffraction reflection at 4.15 A to a broad band centered at 4.5 A. Electron density profiles of gel-phase C24-SM bilayers contain two terminal methyl dips in the center of the bilayer, indicating that the lipid hydrocarbon chains partially interdigitate so that the long saturated 24-carbon acyl chains in one monolayer cross the bilayer center and appose the shorter sphingosine chains from the other monolayer. The incorporation of cholesterol adds electron density to the hydrocarbon chain region near the head group and removes the double terminal methyl dip. These wide- and low-angle X-ray data indicate that cholesterol packs into the hydrocarbon chain region near the sphingomyelin head group, fluidizes the methylene chains near the center of the bilayer compared to the gel phase, and reduces the extent of methylene chain interdigitation.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed1992

Interbilayer interactions between sphingomyelin and sphingomyelin/cholesterol bilayers.

Pressure versus fluid spacing relations have been obtained for sphingomyelin bilayers in the gel phase and equimolar sphingomyelin/cholesterol in the liquid-crystalline phase by the use of X-ray diffraction analysis of osmotically stressed aqueous dispersions and oriented multilayers. For interbilayer separations in the range of 5-20 A, the repulsive hydration pressure decays exponentially with increasing fluid spacing. The decay length (lambda) of this repulsive pressure is about 2 A for both bovine brain and N-tetracosanoylsphingomyelin, similar to that previously found for phosphatidylcholine bilayers. However, both the magnitude of the hydration pressure and the magnitude of the dipole potential (V) measured for monolayers in equilibrium with liposomes are considerably smaller for sphingomyelin than for either gel or liquid-crystalline phosphatidylcholine bilayers. Addition of equimolar cholesterol increases both the magnitude of the hydration pressure and the dipole potential. These data suggest that the magnitude of the hydration pressure depends on the electric field at the interface as given by (V/lambda)2. For sphingomyelin bilayers, there is a sharp upward break in the pressure-fluid spacing relation at an interbilayer spacing of about 5 A, indicating the onset of steric hindrance between the head groups of apposing bilayers.

Animals↗

PubMed1992

Gene conversion confined to a direct repeat of the acceptor splice site generates allelic diversity at human glycophorin (GYP) locus.

The glycophorin locus (GYP) on the long arm of chromosome 4 encodes antigens of the MNSs blood group system and displays considerable allelic variation among human populations. The genomic structure and organization of a variant glycophorin allele specifying a novel Miltenberger (Mi)-related phenotype, MiX, were examined. This variant probably arose from a gene conversion event involving a direct repeat of the acceptor splice site. Southern blot analysis indicated that MiX gene derived its 5' and 3' portions from glycophorin B or delta gene but its internal part from glycophorin A or alpha gene. Genomic sequences encompassing the rearranged regions of the MiX gene were amplified by single copy polymerase chain reaction. Direct DNA sequencing showed that during the formation of MiX gene, a short stretch of alpha exon III with a donor splice site has replaced a silent sequence in the delta gene containing a cryptic acceptor splice site. The upstream delta-alpha breakpoint is flanked by the direct repeats of the acceptor splice site, whereas the down-stream alpha-delta breakpoint is located in the adjacent intron. This segmental transfer produced a new composite exon whose expression not only transactivated a portion of silent sequence but also created intraexon and interexon hybrid junctions that characterize the antigenic specificities of MiX glycophorin. The identification of MiX as yet another delta-alpha-delta hybrid different from MiIII and MiVI in gene conversion sites suggests that shuffling of expressed and unexpressed sequences through particular genomic DNA motifs has been an important mechanism for shaping the antigenic diversity of MNSs blood group system during evolution.

Alleles↗

PubMed1992

Elliptocytosis associated with an abnormal alpha glycophorin.

A case of elliptocytosis associated with an undescribed abnormal alpha glycophorin (alpha GP) is reported. Using immunoblotting techniques, a clear-cut minor band 6' was detected emerging just behind the monomer of delta GP (band 6) when probed with anti-alpha GP antiserum. It also reacted with anti-peptide C antiserum, suggesting that this new band with a molecular weight of 24 K is related to the structural alteration of alpha GP and not delta GP. The erythrocyte membrane proteins of the patient exhibited a quite normal pattern, with a normal alpha spectrin/beta spectrin ratio, but the reaction with anti-protein 4.1 serum confirmed the increase in proteolytic susceptibility of her protein 4.1. The results of DNA mapping implied that the abnormality may be due to a short deletion of the heterozygote. The significance of deviation involving the alpha GP and protein 4.1 to the elliptocytic change of erythrocyte shape is briefly discussed.

Aged↗

PubMed1992

Detection of blood group surface antigens of urinary bladder tumours using monoclonal antibodies with the avidin-biotin complex technique.

We examined 8 normal bladder transitional epithelia and 65 transitional cell carcinomas of the urinary bladder of various stages and grades for the presence of ABO(H) blood group surface isoantigens using the immunoperoxidase staining via the Avidin-Biotin Complex (ABC) methods. It was found that 27% of patients with grade I tumours, 50% with grade II tumours and 82% with grade III tumours had loss of cell surface isoantigens. When correlated with the clinical stage the tumours showed no surface isoantigens in stage D, while 65% of patients with stage A tumours were positive for surface antigens. From among 37 patients (57%), 28 (43%) survived for more than five years. Our results suggest that surface antigens of transitional cell carcinoma of the urinary bladder tended to disappear as the histologic changes of the tumour progressed. It also was noted that a loss of ABH(O) surface isoantigens was a bad prognostic sign.

ABO Blood-Group System↗

PubMed1992

Effect of NaCl on catalysis of lipid oxidation by the soluble fraction of fish muscle.

Sodium chloride stimulated catalysis of oxidation of phosphatidylcholine liposomes by the soluble fraction of mackerel muscle. Chloride was determined to be the active component of the salt in this system. Sulfate also stimulated lipid oxidation. No difference was observed with either anion among sodium, potassium, or lithium cations. Redox iron was involved in the chloride stimulation of lipid oxidation by the press juice. Part of the chloride stimulation of the press juice was mediated through the high molecular weight (greater than 5 kdalton) fraction. Chloride improved the pro-oxidative effect of ascorbate on rat liver ferritin in vitro. It did not appear that production of chlorine radical by peroxidase was involved in the stimulatory effect of chloride.

Acetylcysteine↗

PubMed1992

Calorimetric studies on the influence of N-methylated headgroups on the mixing behavior of diheptadecanoyl phosphatidylcholine with 1-behenoyl-2-lauroylphosphatidylcholine.

Recent studies of five different phosphatidylcholine/phosphatidylcholine (PC/PC) systems indicate that binary mixtures of phosphatidylcholines in which one component has a normalized chain length difference (delta C/CL) in the range of 0.09-0.40 and the other a delta C/CL in the range of 0.42-0.57 exhibit the phase behavior of a eutectic system. Here, delta C is the effective chain-length difference between the two acyl chains, and CL is the effective length of the longer of the two acyl chains for the same lipid molecule in the gel state. In each mixture, gel phase immiscibility occurs over a wide compositional range due to the difference in the gel phase acyl chain packing properties of each component. Although the mixtures differ in the location of their eutectic horizontal, with respect to temperature, all have a similar eutectic point that occurs at a composition of approximately 40 mol percent of the component with the delta C/CL value in the range of 0.42-0.57. Here, we extend these studies by systematically modifying the headgroup of C(17):C(17)PC and then analyzing the mixing behavior of the modified lipid with C(22):C(12)PC using DSC. Progressive demethylation of the C(17):C(17)PC headgroup leads to an increase in gel phase immiscibility and a decrease in the amount of C(22):C(12)PC that comprises the eutectic composition. The temperature defining the location of the eutectic horizontal, however, remains virtually unchanged in all three phase diagrams. Our results suggest that the eutectic composition is influenced by changes in gel phase acyl chain packing that are dependent on headgroup-headgroup interactions. In contrast, the eutectic nature of the phase diagram and the location of its solidus line are properties of acyl chain interactions that are independent of phospholipid headgroup-headgroup interactions.

Calorimetry, Differential Scanning↗

PubMed1992

Study of the changes in collagen of the tunica albuginea in venogenic impotence and Peyronie's disease.

We identified the collagen type and content of the tunica albuginea in Peyronie's disease and venogenic impotence compared with the tunica albuginea from the donor of the renal transplant and patients with penile injury. Type III collagen was detected obviously in Peyronie's plaque and was also present in venogenic impotence. It can be hardly found in normal controls. The ratios of type III to type I collagen were significantly higher in Peyronie's plaque while there was a moderate increase in venogenic impotence. The scarcity of type V collagen was noted in human tunica albuginea. The decreased percentage of glycine and alanine in Peyronie's disease and venogenic impotence implied the abnormal composition of collagen or presence of noncollagen protein. The results suggest the biochemical aberration of the tunica albuginea might interfere with the normal function of the penile drainage system.

Amino Acids↗

PubMed1992

Effects of pentoxifylline in the hamster zona-free oocyte spermatozoa penetration assay and on spermatozoa transmembrane migration motility.

The effects of pentoxifylline on capacitation, acrosome reaction and motility of spermatozoa in vitro were evaluated by the hamster zona-free oocyte penetration assay and the transmembrane migration method, respectively. The improvement in penetration capacity by the addition of pentoxifylline 40 min before coincubation had a trend toward statistical significance (0.05 less than less than 0.1) in normal fertile men and had statistical significance (p less than 0.05) in asthenospermic patients. There was no improvement by the addition of pentoxifylline 16 h before coincubation. Pentoxifylline significantly increased sperm motility in both normal (p less than 0.001) and asthenospermic patients (p less than 0.05) in the transmembrane migration method. This study showed that pentoxifylline could be used as a stimulant of in vitro sperm motility in male infertility.

Animals↗

PubMed1992

A comparative study with intracavernous injection of prostaglandin E1 versus papaverine for the diagnostic assessment of erectile impotence.

The intracavernous injection of vasoactive drugs is a valuable diagnostic aid and an important tool for the treatment of erectile failure. A comparative study with intracavernous injection of prostaglandin E1 (PGE1) and papaverine was performed in 60 patients with impotence. We evaluated the efficiency and side effects of both agents. The overall positive response rate was 85.0% in the PGE1 group and 65.0% in the papaverine group which suggests PGE1 has a stronger vascular effect. The mean onset of maximal erection was after 9.6 minutes in the PGE1 group and after 6.5 minutes in the papaverine group. The mean maintenance of erection was for 53.2 minutes in the PGE1 group and for 38.6 minutes in the papaverine group. There were no systemic side effects of either agent. Three instances of injection pain and 2 of burning sensation in the penis were noted in the PGE1 group, while in the papaverine group, there were 21 reports of injection pain, 4 of prolonged erection and 2 of burning sensation in the penis. These results suggest that PGE1 is a more desirable vasoactive alternative for the diagnosis of impotence.

Adult↗

PubMed1992

Transurethral resection in children with urethral stricture and occlusion.

Technical considerations of urethral surgery in children are critical because of the small size and delicacy of their urethra. From 1984 to 1989, 10 children with serious traumatic urethral stricture (5 cases) and occlusion (5) were treated satisfactorily by an improved transurethral resection (TUR). The age of the children ranged from 4 to 14 years. The TUR technique, curative effects and prevention of urethral stricture are discussed.

Adolescent↗

PubMed1992

Endoscopic management for traumatic occlusion of posterior urethra.

When traumatic posterior urethral transection occurs with serious pelvic fracture, the patient is usually under severe hemorrhagic shock and multiple injuries. It is of prime importance to treat shock and the associated injuries promptly. As for the urethral disruption a simple suprapubic cystostomy at the moment is preferred. Occlusion of the posterior urethra would eventually appear and can be managed endoscopically 3-6 months later. Fifteen such cases were thus managed from 1984 to 1990 with an improved endoscopic technique with a success rate of 93.3% (14/15). The advantages of this technique and the merits and demerits of various primary urethral reconstruction procedures are discussed.

Adolescent↗

PubMed1992

[Effects of PGE1 on penile blood flow].

From February to July in 1989, 47 patients came to our O.P.D. with the chief complaint of impotence. The average age was 48.3 +/- 10.7 y/o. We applied intracoporeal injection of prostaglandin PGE1 (20 mg); and evaluated its penile blood flow effect by color duplex scanning (Acuson 128). The erectile responses of the test showed that: 6 patients (12.8%) had normal response: and 16 patients (34%) had imperfect response. Altogether, the total positive response rate was 46.8%, and 25 patients (53.2%) showed impaired response. The onset of response was 9.1 +/- 3.6 minutes and the duration of erection was 59.2 +/- 24.7 minutes. The percentage of diameter change of both deep arteries after injection was Rt: 58.1 +/- 41.5%; left: 52.3 +/- 35.6%. The peak velocity of right cavernosal arterial flow after intracoporeal injection was 35.5 +/- 15.9 cm/sec; and that of the left side was 33.2 +/- 16.9 cm/sec. There was no correlation between the increment of peak velocity of the deep arterial flow and the erection grade. The same phenomenon was also found between the increased change in the diameter of the deep artery and the erection grade. 16 patients (34.1%) experienced tolerable pain during the procedure. Two patients (4.3%) experienced dizzines and discomfort due to venous leakage. No priapism was found. This study suggests PGE1 may be an excellent potential alternative to other vasoactive drug with less complication in the diagnosis and treatment of impotence. But the cost and stability were its shortcoming.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

PubMed1992

Methotrexate, vinblastine, adriamycin and cisplatin (M-VAC) for advanced TCC of urothelium.

After the introduction of methotrexate, vinblastine, adriamycin and cisplatin combination (M-VAC) chemotherapy for transitional cell carcinoma (TCC) of the urothelium, the reported response and survival rates improved when compared with the previous regimens. From July 1989 to March 1991, 43 consecutive cases of invasive or metastatic TCC that had received at least one course of M-VAC treatment were collected by a computer-assisted search and analyzed. The overall response rate, including complete response (CR) and partial response (PR), was 44% (CR, 16%; PR, 28%). Tumors originating from the renal pelvis or bladder responded better than those from the ureter (kidney, 57%; bladder, 42%; and ureter 30%). Lymph node, soft tissue, lung metastases and local recurrent tumors had a greater chance of response than bone or liver metastases. Although patients from the blackfoot disease endemic area seemed to respond better than those from the nonendemic area, there was no statistically significant survival benefit. The duration of follow-up ranged from nine to 38 months. The length of survival of nonresponders ranged from one month to 19 months (median, eight months; mean, seven months). Ten of the 19 responders relapsed, and the others were still responding. Three patients (7%) survived two years, disease-free. Although the response rate improved, the chance of long-term survival was still unsatisfactory in our study.

Adult↗

PubMed1992

Choriocarcinoma presenting as a unilateral renal mass and gross hematuria in a male: report of a case.

Choriocarcinoma of the kidney, either primary or metastatic, is rarely reported in the literature. We encountered a male patient with choriocarcinoma of the right kidney. The patient initially presented with fever, gross hematuria and flank pain. He had initially been unsuccessfully treated for bilateral renal stones for four months before an accurate diagnosis was made. The disease was verified only after a resection of the right kidney and meticulous examination of microscopic sections of the tumor. Further immunohistochemical study strongly supported the diagnosis of choriocarcinoma. The tumor responded briefly to Cisplatinum, Vinblastine and Bleomycin (PVB) treatment. The patient died of brain metastasis and respiratory failure four months after starting systemic chemotherapy.

Choriocarcinoma↗