Risk factors for persistent candidemia infection in a neonatal intensive care unit and its effect on mortality and length of hospitalization.

OBJECTIVE: Candida infections cause substantial morbidity and mortality in neonates. Persistent candidemia has not been associated with increased risk of mortality compared with candidemia of shorter duration. This study sought to determine whether persistent candidemia was associated with increased length of hospitalization or mortality in neonates. STUDY DESIGN: A chart review was conducted of neonates with Candida bloodstream infections (n=37). Demographic, laboratory, pharmacy, nutrition and discharge data were abstracted. Contingency table analysis and logistic regression were used to analyze variables associated with persistent candidemia and mortality. The relationship between length of hospitalization and persistent candidemia was assessed with k-sample equality of medians test. RESULT: Nine patients (24%) had persistent candidemia. Increased time between blood culture draw and initial antifungal therapy was associated with increased incidence of persistent candidemia (P=0.03). Five patients (14%) died before hospital discharge; however, no deaths were attributed to persistent candidemia. Length of hospitalization was not increased with persistent candidemia. A decrease in the ratio of enteral feeding days to hyperalimentation days before collection of the first positive blood culture was significantly associated with an increase in all-cause mortality (P=0.03) and death attributed to candidemia (P=0.04). The risk of all-cause mortality decreased with a history of receiving any enteral feedings before the first positive blood culture (P=0.04), as did death attributed to candidemia (P=0.02). CONCLUSION: A duration of >1 day between the time of blood culture and the initial dose of systemic antifungal treatment places neonates at increased risk for developing persistent candidemia; however, this is not associated with increased mortality.

Fascioliasis in Vietnam.

A confirmed diagnosis of human fascioliasis was rare in Vietnam until 1978 when two cases were reported in humans. Since 1997, we have confirmed 500 cases of human fascioliasis. The majority of cases come from the central provinces of Vietnam: Da Nang, Quang Ngai, Binh Dinh, Phu Yen and Khanh Hoa. Patients were treated in hospitals in Ho Chi Minh City. All had high peripheral blood eosinophilic counts (16-70%) and positive serology with Fasciola gigantica antigen with positive titers of 1/1,600 to 1/12,800. We are unsure whether this represents an endemic pattern of disease or whether improved specific laboratory tools now facilitate better diagnosis. It is also possible that with changes in environmental factors and in the number and breeds of herbivorous domestic animals, Fasciola is increasing in frequency and easily contaminates the food.

Profile of hyaluronidase activity distinguishes carbon dioxide laser from scalpel wound healing.

Hyaluronic acid plays a key role in the process of wound repair. Deposition of this glycosaminoglycan polymer is in turn controlled by levels of the enzyme hyaluronidase. Hyaluronidase activity was examined in a rat incisional skin wound model comparing laser and scalpel wounds. A polyacrylamide gel electrophoresis (PAGE) hyaluronic acid substrate assay was used to detect differences in the rates of appearance, and level, of hyaluronidase activity in wound homogenates. The hyaluronidase activity in laser wounds appeared earlier, had a bimodal distribution, and increased to a higher level than that in scalpel wounds. The origin of hyaluronidase is not clear, but control of its appearance and modulation of its activity may be a more complex process than previously assumed.

Defects in modification of cytoplasmic and mitochondrial transfer RNAs are caused by single nuclear mutations.

Many nucleus-encoded mitochondrial enzymes differ in physical and chemical properties from analogous cytoplasmic enzymes, and it is therefore generally assumed that different genes encode analogous mitochondrial and cytoplasmic enzymes. However, our genetic studies show that for at least two different tRNA modifications, mutations in nuclear genes affect cytoplasmic as well as mitochondrial tRNAs. These studies utilize two yeast genes: TRM1 and TRM2. trm1 cells do not have the enzyme activity necessary to methylate guanosine to N2,N2-dimethylguanosine. trm2 is a new mutation that we describe here. trm2 cells are deficient in tRNA-(uridine-5)methyltransferase, and hence contain tRNA lacking 5-methyluridine or ribothymidine. Other than lacking 5-methyluridine trm2 cells have no obvious physiological defect. These studies also show that the N2,N2-dimethylguanosine and 5-methyluridine modifications are not added to tRNA in an obligatory order, and that 5-methyluridine is not required for removal of intervening sequences from precursor tRNA.

Characterization of tRNA genes in tRNA region II of yeast mitochondrial DNA.

We have isolated individual mitochondrial tRNAs from a petite mutant OI-P2-1 known to contain a limited subset of mitochondrial tRNA genes and have mapped these genes on the wild type genome of the yeast strains MH41-7B and D273-10B. To obtain DNA for fine structure mapping and DNA sequence analysis of these genes, we screened a yeast mitochondrial DNA-pBR322 recombinant bank with the isolated tRNAs. We report here the fine structure mapping of recombinant clones containing the tryptophan, formyl methionine and proline tRNA genes as well as the DNA sequence of the proline tRNA gene. The combination of restriction mapping and DNA sequence analysis has enabled us to locate these genes precisely on the wild type genome and to determine their direction of transcription.

Yeast mitochondrial tRNATrp can recognize the nonsense codon UGA.

DNA sequence analysis of mitochondrial genes that code for some mitochondrial proteins has suggested that the opal terminator, UGA, is used as a sense codon in mitochondria. The complete sequences of both the yeast and human genes coding for cytochrome oxidase subunit II contain UGA codons in the reading frame. When the protein sequences predicted by these DNA sequences are compared with the known protein sequence of bovine mitochondrial cytochrome oxidase subunit II, there are regions of homology, in which UGA codons correspond to tryptophan residues. Therefore it has been suggested that UGA specifies tryptophan in the mitochondrial code. We have isolated a yeast mitochondrial tRNATrp and used it to locate the mitochondrial tRNATrp gene in pBR322-mitochondrial DNA recombinants. DNA sequence analysis of this gene revealed that the mitochondrial tRNATrp anticodon is 5'UCA3'. Because there is a U in the wobble position, this tRNA can recognize and insert tryptophan into a growing polypeptide chain in response to the nonsense codon UGA.

Sequence analysis of two yeast mitochondrial DNA fragments containing the genes for tRNA Ser UCR and tRNA Phe UUY.

Two restriction enzyme fragments containing yeast mitochondrial tRNA genes have been characterized by DNA sequence analysis. One of these fragments is 320 base pairs long and contains a tRNA Ser gene. The corresponding tRNA SER was isolated from yeast mitochondria and its nucleotide sequence also was determined. This mitochondrial tRNA is 90 nucleotides in length, has a G + C content of 38%, and has UGA as the anticodon. A portion of a 680-base-pair DNA fragment containing a tRNA Phe gene was also sequenced. The portion of this gene which codes for the mature tRNA is 75 base pairs in length, has a G + C content of 33%, and contains the anticodon GAA. Neither gene contains an intervening sequence or codes for the 3' CCA terminus. Both are surrounded by regions of more than 90% A + T. The significance of these sequences is discussed.