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D Kao

Publications and source records attributed to D Kao.

9 recordsLinked to original sources
PubMed2001

The 3' Igkappa enhancer contains RNA polymerase II promoters: implications for endogenous and transgenic kappa gene expression.

We have created a kappa transgene in which a polymerase (pol) III promoter replaces the pol II promoter. Two independent transgenic lines show somatic hypermutation of the transgene in B cells from hyperimmunized mice. Both lines transcribe transgenes from the pol III promoter in the liver. However, in spleen and spleen B cell-derived hybridomas, they also transcribe mRNA from pol II promoters located within the 3' kappa enhancer of the preceding transgene copy in a tandem transgene array. The findings demonstrate that in an array of multiple transgenes the expression (and somatic hypermutation) of an individual transgene copy must be considered in the context of the other copies. We also show that sequences around the 3' kappa enhancer in endogenous genes are transcribed. The possible role of these promoters in endogenous kappa gene expression is discussed. An unrelated finding in this study was a novel RNA splice in one hybridoma.

Animals↗
PubMed1999

Design, synthesis, and evaluation of N-aroyloxy-2-thiopyridones as DNA photocleaving reagents.

N-Benzoyloxy-2-thiopyridone (12) was shown to induce single-strand nicks in duplex DNA upon irradiation with visible light (lambda&350 nm). This finding led to the design of a series of compounds, in which an acridinyl nucleus was covalently linked to the N-benzoyloxy-2-thiopyridone unit. These conjugates (15, 16, 17 and 18) were synthesized and evaluated as novel DNA photocleaving reagents. Optimal photocleaving activity was observed for conjugate 16, in which a flexible polymethylene spacer of 4 carbons was used to connect the aminoacridine entity to the thiopyridone. This compound was shown to cleave DNA at low microM concentrations and was approximately two-orders of magnitude more efficient than the parent N-benzoyloxy-2-thiopyridone (12). Furthermore, the DNA cleavage ladders induced by 16 and 12 were found to be identical and of no significant sequence selectivity. These data suggest that the N-aroyloxy-2-thiopyridones can be used for the design of new DNA photocleaving reagents with potential use as 'photofootprinting agents' or as 'site-directed photonucleases'.

Autoradiography↗
PubMed1998

Molecular evidence for multiple origins of Insectivora and for a new order of endemic African insectivore mammals.

The traditional views regarding the mammalian order Insectivora are that the group descended from a single common ancestor and that it is comprised of the following families: Soricidae (shrews), Tenrecidae (tenrecs), Solenodontidae (solenodons), Talpidae (moles), Erinaceidae (hedgehogs and gymnures), and Chrysochloridae (golden moles). Here we present a molecular analysis that includes representatives of all six families of insectivores, as well as 37 other taxa representing marsupials, monotremes, and all but two orders of placental mammals. These data come from complete sequences of the mitochondrial 12S rRNA, tRNA-Valine, and 16S rRNA genes (2.6 kb). A wide range of different methods of phylogenetic analysis groups the tenrecs and golden moles (both endemic to Africa) in an all-African superordinal clade comprised of elephants, sirenians, hyracoids, aardvark, and elephant shrews, to the exclusion of the other four remaining families of insectivores. Statistical analyses reject the idea of a monophyletic Insectivora as well as traditional concepts of the insectivore suborder Soricomorpha. These findings are supported by sequence analyses of several nuclear genes presented here: vWF, A2AB, and alpha-beta hemoglobin. These results require that the order Insectivora be partitioned and that the two African families (golden moles and tenrecs) be placed in a new order. The African superordinal clade now includes six orders of placental mammals.

Africa↗
PubMed1997

Interleukin-4 or interleukin-10 expressed from adenovirus-transduced syngeneic islet grafts fails to prevent beta cell destruction in diabetic NOD mice.

BACKGROUND: We performed ex vivo adenoviral gene transfer in a mouse pancreatic islet transplant model to test the efficacy of this expression system. We then determined whether adenoviral-mediated expression of mouse interleukin (IL) 4 or IL-10 from transduced syngeneic islet grafts could prevent disease recurrence in diabetic nonobese diabetic (NOD) mice. METHODS: An adenoviral vector expressing beta-galactosidase (AdCMV betaGal) was used to transduce BALB/c islets (2.5 x 10(3) plaque-forming units/islet), which were analyzed for glucose responsiveness, islet cell recovery, and efficiency of gene transfer. In vivo function and reporter gene expression were examined with AdCMV betaGal-transduced islet grafts in alloxan-induced diabetic syngeneic recipients. Adenoviruses expressing either IL-4 or IL-10 were used in a similar fashion to infect NOD islets, which were characterized in vitro, as well as transplanted into diabetic syngeneic recipients. RESULTS: In vitro functional studies showed no significant difference between control or transduced islets, with 50+/-4% of AdCMV betaGal-infected islet cells staining positive for beta-galactosidase. Transplant recipients became nomoglycemic within 48 hr after transplant, and, although beta-galactosidase expression decreased over time, it was detectable in the graft for up to 8 weeks. Despite the nanogram quantities of IL-4 or IL-10 produced/day from each graft equivalent in vitro, transduced and transplanted NOD islets failed to prevent disease recurrence. CONCLUSIONS: These results suggest that adenoviruses are efficient for at least medium term gene expression from islets in vivo, but neither IL-4 nor IL-10 alone can prevent autoimmune disease recurrence in NOD mice.

Adenoviridae↗
PubMed1997

Porin polypeptide contributes to surface charge of gonococci.

Each strain of Neisseria gonorrhoeae elaborates a single porin polypeptide, with the porins expressed by different strains comprising two general classes, Por1A and Por1B. In the outer membrane, each porin molecule folds into 16 membrane-spanning beta-strands joined by top- and bottom-loop domains. Por1A and Por1B have similar membrane-spanning regions, but the eight surface-exposed top loops (I to VIII) differ in length and sequence. To determine whether porins, and especially their top loop domains, contribute to bacterial cell surface charge, strain MS11 gonococci that were identical except for expressing a recombinant Por1A, Por1B, or mosaic Por1A-1B polypeptide were compared by whole-cell electrophoresis. These porin variants displayed different electrophoretic mobilities that correlated with the net numbers of charged amino acids within surface-exposed loops of their respective porin polypeptides. The susceptibilities of porin variants to polyanionic sulfated polymers correlated roughly with gonococcal surface charge; those porin variants with diminished surface negativity showed increased sensitivity to the polyanionic sulfated compounds. These observations indicate that porin polypeptides in situ contribute to the surface charge of gonococci, and they suggest that the bacterium's interactions with large sulfated compounds are thereby affected.

Amino Acid Sequence↗
PubMed1996

Gastric emptying of oil from solid and liquid meals. Effect of human pancreatic insufficiency.

Digestion of fat in pancreatic insufficiency (PI) is strongly affected by how rapidly fat enters the duodenum. We postulated that: (1) oil empties faster in PI than in normals and (2) in both, it empties in a load-dependent fashion. We used a gamma camera to test these ideas by comparing gastric emptying of iodine-123 iodinated oil in normal and pancreatic-insufficient subjects after 15 g of free oil were ingested in a small spaghetti meal and 60 g of oil were ingested in a large spaghetti meal and in a milk emulsion. Indium-113m marked gastric emptying of water in the milk. In both groups after all meals, oil emptied fastest initially, slowing later; and oil emptied three to four times faster when 60 g vs 15 g were ingested. There were no significant differences between the groups of subjects with respect to gastric emptying of the spaghetti meals, but the pancreatic-insufficient subjects emptied both oil and water faster from the milk emulsion than did the normal subjects. The slower emptying of oil in the normal subjects was associated with significantly more layering of oil to the top of the intragastric milk emulsion.

Adult↗
PubMed1986

Pursed lips breathing training using ear oximetry.

Pursed lips breathing (PLB) training is often used in the management of patients with chronic obstructive lung disease (COLD). Previous clinical studies have demonstrated that PLB improves arterial oxygen saturation (SaO2) and CO2 removal as well as relieving dyspnea. Twelve hypoxemic subjects with stable COLD were randomly assigned to either the pursed lips (P) or control group consisting of general relaxation (R). The SaO2 was monitored via ear oximetry, and respiratory rate and tidal volume were monitored using a strain gage transducer and the minute volume was calculated. The PLB was taught by an experienced instructor using the ear oximeter as a monitoring display with a goal toward increasing SaO2. The subject was taught general relaxation (Rlx) with the aid of pleasant music. We compared PLB and Rlx treatments using an A-B-A crossover study design. In both groups, PLB significantly improved SaO2 over baseline (p less than 0.001) whereas Rlx did not. We conclude that patients can learn to increase their SaO2 by PLB using ear oximetry adjunctively.

Aged↗
PubMed1975

Advances in the treatment of pulmonary alveolar proteinosis.

Our currecnt technique for lung lavage is described. This technique can be safely and effectively applied to patients with pulmonary alvelar proteinosis who require therapy. Normal saline alone is as effective a solution as one containing heparin and acetylcysteine. Chest percussion during lung lavage considerably enhances the yeild of each lavage and thus shortens the time required for the procedure. Lung lavage results in remarkable clearing of the chest roentgenogram and reversal of the physiologic defects and symptoms of the patient by the following day. In our experience this improvement lasts for at least one year.

Acetylcysteine↗