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Biomedical subjects

K S Chiang

Publications and source records attributed to K S Chiang.

At least 19 recordsLinked to original sources

Intrapulmonary artery infusion of urokinase for treatment of massive pulmonary embolism: a review of 26 patients with and without contraindications to systemic thrombolytic therapy.

BACKGROUND: Pulmonary emboli (PE) are a common event seen in over 600,000 patients a year. Occurring suddenly, PE often result in a high rate of mortality. To combat the high rate of mortality, more aggressive therapies including the use of thrombolytics are often indicated. The use of intrapulmonary artery infusion of urokinase has been shown to promote rapid resolution of emboli and restoration of normal pulmonary hemodynamics. HYPOTHESIS: The study was undertaken to review the effectiveness and safety of pulmonary artery infusion of urokinase in 26 patients with and without contraindications to the use of systemic thrombolytic therapy. METHODS: We reviewed the outcomes of 26 patients who received infusion of urokinase, using a usual loading dose of 4,000 U/kg body weight given as a bolus, followed by 4,000 U/kg/h for 12 to 24 h, using either/or unilateral or bilateral infusions. Pulmonary angiograms were obtained prior to and following the urokinase infusions. RESULTS: Intrapulmonary artery infusion of urokinase was given to 26 patients, 9 of whom had contraindications to the use of systemic thrombolytic therapy. Six patients were recent post operative, one was receiving oral anticoagulants, one was receiving chemotherapy with bleeding complications, and one had received cardiopulmonary resuscitation. Twenty of the patients returned to their baseline state (normal heart rate, blood pressure, and p02), one was minimally improved, and five deaths occurred. Of the five deaths, three occurred within 1 h of starting urokinase infusion, the remaining two died more than 36 h after treatment with urokinase as a result of their basic underlying disease. Minor bleeding occurred from puncture sites, two hematomas occurred at the puncture site, and there were two gastrointestinal bleeds, one of which occurred a week post urokinase therapy while the patient was receiving heparin and coumadin. No central nervous system bleeds occurred and no transfusions were required as a result of urokinase intrapulmonary artery infusions. The overall mortality rate in this series was 11.5%. CONCLUSIONS: Intrapulmonary artery infusion of urokinase in extensive pulmonary embolism is a safe and efficient treatment in patients with and without contraindication to the use of systemic thrombolytic therapy. With a usual loading dose of 4,000 U/kg body weight, followed by an infusion of 4,000 U/kg/h for 12 to 24 h, it produces significant and rapid resolution of pulmonary emboli with a low morbidity and mortality rate. In our series, the mortality rate was 11.5%, and none of the deaths was the direct result of urokinase therapy.

Adult↗

Population heterogeneity of higher-plant mitochondria in structure and function.

Mitochondria of rapidly developing mungbean seedlings were fractionated into four populations: two density classes, each from a 1500S and a 150S pellet. Each of the four populations exhibited cytochrome c oxidase (COX) activity and contained mitochondrial DNA and cardiolipin; plastid and glyoxysome content were found to be relatively low. Five mitochondrial membrane proteins, COXII/III, ATPase alpha/beta and porin, and a matrix enzyme, manganese superoxide dismutase (MnSOD), were detected by immunoblots in all four populations. Another matrix enzyme, pyruvate dehydrogenase was detected only in the two respiratory-competent 1500S populations. The two 150S populations contained a previously unidentified organelle that lacked demonstrable respiratory capability. This organelle, which we have tentatively referred to as "slow-sedimenting (ss-) mitochondrion", was small in size (below light-optics resolution, 70-300nm, majority < or =200nm) and possessed a peculiar looking boundary membrane, ribosomes, and an occasional prominent electron-dense spot. Characteristically, ss-mitochondria were almost always in contact with a filament-aligned membrane-like structure of varying length. Cristae structure, while undetected in small ss-mitochondria, appeared in larger individuals. Typical mitochondria were found in the denser 1500S population, while the lighter 1500S population consisted of 300-800 nm mitochondria exhibiting a varying degree of size-dependent inner membrane folding. Using electron microscopy (EM) immunolocalization and serial sectioning, we have identified in situ organelles resembling in size and in fine structure the ss-mitochondria, which also exhibit a size-dependent folding of the inner membrane. These results suggest that small ss-mitochondria may undergo a progressive development in situ. Taken together, our findings demonstrate the existence of a pattern of structure-function-coordinated gross heterogeneity among mitochondria. This pattern of mitochondrial heterogeneity, characterized both in isolated mitochondria and in situ, implies that small ss-mitochondria may represent a type of "nascent mitochondria" derived from a yet unidentified mitochondria-propagation mode operating during rapid seedling growth. Mitochondrial division by binary fission, characterized by the appearance of dumbbell-shaped intermediates, was also detected.

Cardiolipins↗

Embolectomy of a Bird's Nest Vena Caval Filter.

In this case report we describe a successful embolectomy of a partially migrated Bird's Nest Caval Filter with attached embolic material. We used transesophageal echocardiography to guide the surgical approach. The patient recovered uneventfully from both the embolectomy and the subsequent pelvic operation.

Echocardiography, Transesophageal↗

Metastasis to the bladder from pancreatic adenocarcinoma presenting with hematuria.

Pancreatic adenocarcinoma infrequently involves the urinary tract. Hematuria may result from either direct invasion of the kidneys or from metastases to the urinary tract. The bladder may be involved in the late stages from metastases, but rarely is it associated with hematuria since mucosal involvement is very unusual. We report a second case of bladder metastases and hematuria as a presenting symptom of pancreatic carcinoma.

Adenocarcinoma↗

Protein Synthesis in Isolated Mitochondria of Rice (Oryza sativa L.) Seedlings.

For studies of in organello mitochondrial protein synthesis in rice, Oryza sativa L., conventional surface-sterilization procedures were demonstrated to be ineffective. Because of the over-whelmingly efficient [(35)S]methionine utilization by contaminating bacteria, even "essentially bacteria-free" rice mitochondria were shown to be unsuitable for the study of in organello protein synthesis. We developed a procedure to obtain a bacteria-free preparation of rice mitochondria. Such mitochondria favored a membrane-dependent ATP-generating system over an external ATP-generating system as the energy supplement for in organello protein synthesis. Two distinct classes of [(35)S]methionine-labeled, cycloheximide-insensitive products were detected: an electrophoretically unresolved population and a set of some 22 to 27 discrete polypeptide species, each with a characteristic electrophoretic mobility and relative abundance.

Journal Article↗

Use of a fibre-optic hydrophone in measuring acoustic parameters of high power hyperthermia transducers.

A fibre-optic hydrophone consisting of a polarisation-maintaining fibre carrying light from a laser source has been used to measure the acoustic output parameters of a single focused hyperthermia transducer and a six-transducer assembly. Beam profiles of the transducers were measured using the fibre-optic hydrophone and the results compared with those obtained using a PVDF hydrophone. The acoustic power output from the hyperthermia transducer was measured using a radiation force balance. It was observed that the root mean square voltage of the fibre-optic hydrophone output is proportional to the square root of the acoustic power up to more than 80 W. It was also observed that, under continuous-wave operation, the fibre optic hydrophone can stand up to very high power (more than 200 W) without being damaged. As its sensing element is the fibre itself, whose diameter is considerably narrower than the width of the ultrasonic beam, it can provide resolution of about 80 microm in beam profile measurement. The fibre is a line sensor and a computer tomographic technique is used to recover the pressure profile from the hydrophone output voltage. In typical clinical operations, the six-transducer assembly is driven with less than 150 W of electrical power input. In such cases, each individual transducer receives less than 25 W of input power and non-linearity and generation of high frequency harmonics at the focus is not a significant problem.

Acoustics↗

Characterization of a spontaneously segregating Cf16-v1 lysogen of Xanthomonas campestris pv. citri.

Filamentous phage Cf16 undergoes a unique neolysogenic infectious cycle in Xanthomonas campestris pv. citri and generates stable lysogens. In contrast, we have isolated a distinctive unstable lysogen, designated LW. This new lysogen segregated spontaneously into three nonparental types, each with a unique combination of colony morphology, phage-producing capacity, and phage genome content. In a given population of LW lysogens the segregation frequency of these types varied randomly with drastic fluctuations from experiment to experiment. Heat and UV treatment failed to increase the segregation frequency with a magnitude matching the sporadic intrinsic fluctuations. The characteristics of an LW lysogen were transmitted through the phage it released. Designated as Cf16-v1, this phage, which produced clear instead of turbid plaques as its progenitor Cf16, was exceedingly unstable in the host cell. Only 4% of the infected cells, rather than 95% as in the case of Cf16, retained the phage genome and completed the neolysogenization process. The prophage integration site on the host chromosome, however, appeared to be the same for both phages.

Bacteriophages↗

Nucleotide sequences involved in the neolysogenic insertion of filamentous phage Cf16-v1 into the Xanthomonas campestris pv. citri chromosome.

Following a protracted carrier state in the infected cell, filamentous bacteriophage Cf16-v1 neolysogenizes Xanthomonas campestris pv. citri by inserting the phage genome into the host chromosome. The integration region in the phage and the host chromosome, respectively, and the two junctions in the lysogen chromosome were isolated and their nucleotide sequence was determined. The phage and host attachment sites shared an identical 15-bp "core," 5'-TATACATTATGCGAA-3'. Located on either side of each core were two unique arm sequences. Each of the two phage-host junctions contained an intact core flanked by a hybrid combination of phage and host arm sequences. A 10-bp symmetrical sequence arranged as inverted repeats with 1-bp spacing straddled the core sequence. A 10-bp repeated sequence, 5'-GCGCTATGGC-3', was found distal to the core in opposite orientation at the phage attachment site, while an abbreviated form of this sequence was present in the host attachment site. These sequence characteristics indicate that neolysogenic insertion of Cf16-v1 was accomplished by a site-specific recombination mechanism similar to lambda integration. However, in contrast to lambda, the phage and the host attachment sites in the Cf16-v1 system contained a high G + C nucleotide bias (except for the core sequence itself).

Bacteriophages↗

Differential stability of filamentous phage genomes in Xanthomonas campestris pv citri.

Stability of carrier state in filamentous phage-infected Xanthomonas campestris pv citri varied drastically even for closely related phage types. The spontaneous curing frequency for cells infected with Cf16-12, Cf16, Cf16-v1 and Cf was 1, 5, 96 and 100%, respectively. The size of the phage replicative-form (RF) pool which built up rapidly at the onset of Cf16 infection was critical to the maintenance of the carrier state and the eventual integration of the prophage. A correlation in stability between phage carrier state in infected cells and lysogeny was found for these phages. The past history of a phage infection altered the response of the cured host to reinfection. In those cured cells which remained susceptible, the stability of the reinfecting phage genome was not altered appreciably, while a distinctive new plaque morphology appeared in greater than 50% of these cells. These alterations were not dependent on the prophage integration prior to curing, and no phage DNA was detected in cured cells by blot hybridisation. Notwithstanding these changes, the sites of phage integration in cured cells remained the same as the original infection on both the phage RF and the host chromosome.

Bacteriophages↗

The persistence of maternal inheritance in Chlamydomonas despite hypomethylation of chloroplast DNA induced by inhibitors.

We have used inhibitors of methylation to evaluate the proposal that the extent of methylation of chloroplast DNA ( cpDNA ) of the mating type-plus (mt+) parent occurring during gametogenesis in wild-type Chlamydomonas renhardtii is directly correlated with the uniparental transmission of chloroplast genes by this parent [ Sager , R., Grabowy , C. & Sano , H. (1981) Cell 24, 41-47]. As detected by high-pressure liquid chromatography, the methylation of cpDNA was at its lowest level in the vegetative stage; the mt+ cells had a deoxycytidine methylation index (the percentage of deoxycytidine methylated) of 0.5, while the mating type-minus (mt-) index was lower by at least a factor of 3. This basal level of cpDNA methylation increased more than 20-fold after gametogenesis to give a methylation index of 12.1 and 4.3 for mt+ and mt- gametes, respectively. Another striking increase was detected at the 7-hr-zygote stage, resulting in the methylation of nearly half of the total deoxycytidine residues. The extent of zygotic cpDNA methylation was shown to be dependent on the preexisting methylation level of both parental gametic cpDNAs . L-Ethionine and 5-azacytidine effectively inhibited cpDNA methylation during gametogenesis and ensuing zygotic development as shown by both Hpa II/Msp I digestion patterns and HPLC. The transmission of chloroplast genes was analyzed concomitantly with the inhibitor studies. The two inhibitors produced different patterns of inhibition of methylation in mt- and mt+ cells at a given developmental stage. Our overall results demonstrate that the extent of mating type-specific and gamete-specific methylation during gametogenesis is not correlated with the frequency of maternal transmission of chloroplast genes.

Azacitidine↗

Genetics of Chlamydomonas reinhardtii diploids. II. The effects of diploidy and aneuploidy on the transmission of non-Mendelian markers.

The transmission of two non-Mendelian drug resistance markers has been studied in crosses of Chlamydomonas reinhardtii involving diploids and aneuploids with different mating type genotypes. Under normal laboratory conditions for gametogenesis, mating and zygote maturation, the transmission pattern of the non-Mendelian markers sr-u-1 (resistance to streptomycin) and spr-u-1-27-3 (resistance to spectinomycin) is primarily determined by the mating type genotypes of the parental cells. Our results confirm and expand an earlier observation suggesting that an apparent codominant function of the female (mt+) allele in regulating chloroplast gene transmission in meiosis appears to be distinct and separate from its recessive function in regulating mating behavior. The chloroplast DNA complement (as indexed by the number of extranuclear DNA-containing bodies) may exert a secondary effect on the transmission of these markers. Within a mating type group (mt+/mt- or mt-/mt-) a cell line with more chloroplast DNA tended to transmit its non-Mendelian markers more frequently than a cell line with less chloroplast DNA.

Aneuploidy↗

Selective incorporation of thymidine in the organelle DNA of Polytoma obtusum.

Polytoma obtusum was found to selectively incorporate exogenous thymidine into its leukoplast DNA. The nuclear DNA was unable to incorporate [3H]thymidine, although both DNA species could be labeled with radioactive adenine with similar efficiencies. The mitochondrial DNA (mitDNA), which had a buoyant density of 1.714 g/ml and was banded slightly on the heavier side of the nuclear DNA peak, was also found to incorporate a small amount of [3H]thymidine. These observations suggest that P. obtusum lack cytoplasmic thymidine kinase, whereas the enzyme is present in both leukoplast and mitochondria.

Adenine↗

Genetics of Chlamydomonas reinhardtii diploids. I. Isolation and characterization and meiotic segregation pattern of a homozygous diploid.

A strain of Chlamydomonas reinhardtii has been investigated which, when mated with known wild-types, produces very few viable germination products and transmits its Mendelian markers to more than half of those products. Cytogenetic observations, fluorometric measurements of DNA and genetic data all suggest that the strain, d mt-ery-M3a sr-u-1 is a stable homozygous diploid. This strain has twice as many nuclear chromatin bodies at metaphase and twice as much DNA as its haploid progenitor, and the phenotypes of its meiotic progeny are consistent with predictions based on triploid meiosis. Data from crosses involving d mt-ery-M3a sr-u-1 and from crosses involving hybrid diploids indicate that the frequency of second division segregation increases in triploid zygotes and that mitotic segregation following triploid meiosis is a frequent event which may more often result from mitotic recombination than from chromosome loss.

Chlamydomonas↗

Pigment mutants of Chlamydomonas with deformed plastids and increased levels of chloroplast nucleic acids.

The chloroplast ultrastructure of two Chlamydomonas reinhardtii pigment variant mutants, U3N and U3A, is strikingly different from that of the wild type. The mutant chloroplast has greatly lowered levels of chlorophyll a and b, and lacks the usual ordered thylakoid membrane structure. The amount of chloroplast ribosomes is increased, but the pyrenoid and surrounding starch grains appear to be unaltered. Our biochemical analyses have shown that, while the properties of chloroplast DNA, ribosomal RNA, and ribosomes in these mutants appeared to be normal, their relative amounts per cell increased markedly when compared to the wild type. In U3N these increases were approximately 60% for chloroplast DNA and 80% for chloroplast ribosomes. However, the ratio of chloroplast rDNA genes to total chloroplast DNA remained unchanged as shown by DNA-rRNA hybrdization. We propose that (1) The enhanced level of chloroplast ribosomes in these mutants is a direct consequence of the elevated amount of chloroplast DNA. Both of these increases may, in turn, arise from defective mechanism for their control. (2) These mutants grow successfully in the absence of functional photosynthesis, provided an external carbon source is available to them, but functional plastid DNA, ribosomes and protein synthesis may still be a requirement for normal starch metabolism.

Chlamydomonas↗

Characterization of thymidine kinase and phosphorylation of deoxyribonucleosides in Chlamydomonas reinhardti.

Using gel filtration chromatography, we find a single peak of deoxythymidine phosphorylating activity in Chlamydomonas reinhardti. This activity has characteristics of a thymidine kinase, in that (1) it will utilize ATP (or dATP) or CTP (or dCTP) as phosphoryl donor, but not AMP or phenyl phosphate, and (2) it is inhibited by dTTP (and less so by dTDP, dUTP, and dUDP) but is unaffected by 3'-5' cyclic AMP. Partially purified chlamydomonas thymidine kinase has a pH optimum near 8.5, and a molecular weight of 80,000 to 85,000 daltons. Kinetic studies indicate a ping-pong mechanism with a Km for thymidine of 1.5 x 10(-7) moles per liter. 5-Bromo- and 5-fluorodeoxyuridine, and to a lesser degree deoxyuridine, are competitive inhibitors, but significant phosphorylation of these nucleotides could not be demonstrated in vitro by thymidine kinase. While thymidine is phosphorylated to dTMP by crude Chlamydomonas extracts, greater than 80% of the product formed by the partially purified enzyme is dTTP. Further, the gel filtration elution position of the single deoxythymidylate kinase activity present in cell extracts coincides with that of thymidine kinase. These results suggest that a multifunctional enzyme, rather than three separate phosphorylating activities, may be responsible for dTTP formation.

Adenosine Triphosphate↗