Cytomegalovirus is the most common pathogen causing congenital infection and can result in significant neurodevelopmental adverse outcomes. For this reason, it is the standard of care in many regions to treat congenital cytomegalovirus infection involving the brain with six weeks of ganciclovir. There have been no reports in the published literature of significant cytomegalovirus neonatal infection in infants previously treated for congenital infection.
A preterm male infant with congenital symptomatic cytomegalovirus infection was initially treated with over 8 weeks of ganciclovir between the ages of 3 and 14 weeks. At four months chronologic age, just prior to planned discharge, he developed an episode of life-threatening multisystem cytomegalovirus disease notable for severe pneumonitis, encephalitis, hepatitis, and disseminated intravascular coagulation. This disease resolved after re-treatment with a prolonged course of intravenous ganciclovir and oral valganciclovir.
Clinicians should be aware of the possibility of recurrence of congenital cytomegalovirus infection, especially in preterm infants. Serial plasma cytomegalovirus viral load monitoring may have a role in the management of premature infants treated with ganciclovir; had the diagnosis of recrudescent cytomegalovirus infection been considered sooner, specific therapy might have been more quickly initiated and perhaps further morbidity would have been prevented.
Cytomegalovirus; Congenital infection; Ganciclovir
Background and Objectives
Sodium thiosulfate (STS) reduced calcium stone formation in both humans and genetic hypercalciuric stone forming (GHS) rats. We sought to measure urine chemistry changes resulting from STS administration in people.
Design, Setting, Participants & Measurements
STS was given to healthy and hypercalciuric stone forming adults. Five normal non-stone forming adults (mean age 33 years), and 5 people with idiopathic hypercalciuria and calcium kidney stones (mean age 66 years) participated. Two baseline 24-hour urine collections were performed on days 2 and 3 of 3 days of self-selected diets. Subjects then drank STS 10 mmol twice a day for 7 days and did urine collections while repeating the self-selected diet. Results were compared by non-parametric Wilcoxon signed rank test. The primary outcome was the resulting change in urine chemistry.
STS administration did not cause a significant change in urinary calcium excretion in either group. In both groups, 24 hour urinary ammonium (P = 0.005) and sulfate excretion (P = 0.007) increased, and urinary pH fell (P = 0.005); citrate excretion fell (P<0.05) in hypercalciuric participants but not in non-stone formers. Among stone formers with hypercalciuria, 3 of 5 patients had measurement of serum HCO3 concentration after the STS period: it did not change. The net effect was an increase in supersaturation of uric acid, and no change in supersaturation of calcium oxalate or calcium phosphate.
The basis for studies demonstrating that STS prevented stones in rats and people was not reflected by the changes in urine chemistry reported here. Although serum HCO3 did not change, urine tests suggested an acid load in both non-stone forming and hypercalciuric stone-forming participants. The long term safety of STS needs to be determined before the drug can be tested in humans for long-term prevention of stone recurrence.
The microbiology and epidemiology of UTI pathogens are largely unknown in Botswana, a high prevalence HIV setting. Using laboratory data from the largest referral hospital and a private hospital, we describe the major pathogens causing UTI and their antimicrobial resistance patterns.
This retrospective study examined antimicrobial susceptibility data for urine samples collected at Princess Marina Hospital (PMH), Bokamoso Private Hospital (BPH), or one of their affiliated outpatient clinics. A urine sample was included in our dataset if it demonstrated pure growth of a single organism and accompanying antimicrobial susceptibility and subject demographic data were available.
A total of 744 samples were included. Greater than 10% resistance was observed for amoxicillin, co-trimoxazole, amoxicillin-clavulanate, and ciprofloxacin. Resistance of E. coli isolates to ampicillin and co-trimoxazole was greater than 60% in all settings. HIV status did not significantly impact the microbiology of UTIs, but did impact antimicrobial resistance to co-trimoxazole.
Data suggests that antimicrobial resistance has already emerged to most oral antibiotics, making empiric management of outpatient UTIs challenging. Ampicillin, co-trimoxazole, and ciprofloxacin should not be used as empiric treatment for UTI in this context. Nitrofurantoin could be used for simple cystitis; aminoglycosides for uncomplicated UTI in inpatients.
Little is known about the microbiology of diarrhoeal disease in Canada's Arctic regions. There are a number of limitations of conventional microbiology testing techniques for diarrhoeal pathogens, and these may be further compromised in the Arctic, given the often long distances for specimen transport.
To develop a novel multiple-target nanolitre real-time reverse transcriptase (RT)-PCR platform to simultaneously test diarrhoeal specimens collected from residents of the Qikiqtani (Baffin Island) Region of Nunavut, Canada, for a wide range of bacterial, parasitic and viral agents.
Diarrhoeal stool samples submitted for bacterial culture to Qikiqtani General Hospital in Nunavut over an 18-month period were tested with a multiple-target nanolitre real-time PCR panel for major diarrhoeal pathogens including 8 bacterial, 6 viral and 2 parasitic targets.
Among 86 stool specimens tested by PCR, a total of 50 pathogens were detected with 1 or more pathogens found in 40 (46.5%) stool specimens. The organisms detected comprised 17 Cryptosporidium spp., 5 Clostridium difficile with toxin B, 6 Campylobacter spp., 6 Salmonella spp., 4 astroviruses, 3 noroviruses, 1 rotavirus, 1 Shigella spp. and 1 Giardia spp. The frequency of detection by PCR and bacterial culture was similar for Salmonella spp., but discrepant for Campylobacter spp., as Campylobacter was detected by culture from only 1/86 specimens. Similarly, Cryptosporidium spp. was detected in multiple samples by PCR but was not detected by microscopy or enzyme immunoassay.
Cryptosporidium spp., Campylobacter spp. and Clostridium difficile may be relatively common but possibly under-recognised pathogens in this region. Further study is needed to determine the regional epidemiology and clinical significance of these organisms. This method appears to be a useful tool for gastrointestinal pathogen research and may also be helpful for clinical diagnostics and outbreak investigation in remote regions where the yield of routine testing may be compromised.
multiplex real-time PCR; detection; pathogens; Campylobacter spp.; Cryptosporidium spp.; Clostridium difficile; viral agents; diarrhoea; gastroenteritis; Nunavut; Arctic
Background and Purpose
Oxalobacter formigenes (OF) may play a protective role in preventing calcium oxalate stones. This is the first prospective study to evaluate the effect of antibiotics on OF colonization. Intestinal colonization by OF is associated with reduced urinary oxalate excretion. Exposure to antibiotics may be an important factor determining rates of colonization.
Materials and Methods
The effect of antibiotics on OF colonization was compared in two groups: A group receiving antibiotics for gastric infection with Helicobacter pylori (HP) and a group without HP whose members were not receiving antibiotics. OF colonization in stool was detected by oxalate degradation at baseline and after 1 and 6 months.
The prevalence at baseline of intestinal colonization with OF was 43.1% among all patients screened. Among the 12 patients who were positive for OF who did not receive antibiotics, 11 (92%) had OF on stool tests at 1 month and 6 months. Of the 19 participants who were positive for OF and who received antibiotics for HP, only 7 (36.8%) continued to be colonized by OF on follow-up stool testing at 1 and 6 months (P=0.003 by Fisher exact test). Amoxicillin and clarithromycin caused 62.5% of subjects to become negative for OF at 1 month; 56.2% remained negative for OF at 6 months.
Antibiotics for HP infection effectively reduced colonization with OF, an effect present at 1 and 6 months after treatment. The lasting elimination of OF could be associated with hyperoxaluria and be a factor in recurrent kidney stone disease.
Patients treated with erythropoiesis-stimulating agents (ESAs) to a hemoglobin (Hb) level >12.0 g/dl have increased risk of multiple complications, including death. The optimal Hb target for ESA use has not been established. We hypothesized that reducing the target Hb would prevent levels >12 g/dl and lead to significant cost savings.
Our target Hb range was reduced to 9–11 g/dl from 10–12 g/dl. Thirty-five chronic hemodialysis (HD) patients received erythropoietin (EPO) and intravenous iron from January to December 2009. Data analysis included: Hb level, EPO dose, transferrin saturation and ferritin levels. EPO was administered via subcutaneous injection weekly or twice weekly.
The mean monthly Hb level changed from 11.2 to 10.6 g/dl. The percentages of patients with mean Hb >10.0, 12.0 and 13.0 g/dl were 82 ± 6.5, 10 ± 5.6 and 1.8 ± 1.9%, respectively. Weekly EPO dose decreased from 9,500 to 5,600 units, a 40% reduction per dose per patient and costs. The savings exceeded USD 60,000 per year for 35 patients. More than 80% of patients had transferrin saturation >20% and ferritin >200 ng/ml throughout the entire period.
Lowering the target Hb range to 9–11 g/dl in HD patients achieved quality anemia management, avoided values >12.0 g/dl and resulted in cost savings. A minimal reduction in quality of life and no change in cardiovascular morbidity or mortality would be expected. The study has important implications in the new American bundled reimbursement model.
Anemia; Chronic kidney disease; Erythropoietin; Hemodialysis; Iron; Kidney failure
Rapid diagnosis of GAS pharyngitis may improve patient care by ensuring that patients with GAS pharyngitis are treated quickly and also avoiding unnecessary use of antibiotics in those without GAS infection. Very few molecular methods for detection of GAS in clinical throat swab specimens have been described.
We performed a study of a laboratory-developed internally-controlled rapid Group A streptococcus (GAS) PCR assay using flocked swab throat specimens. We compared the GAS PCR assay to GAS culture results using a collection of archived throat swab samples obtained during a study comparing the performance of conventional and flocked throat swabs.
The sensitivity of the GAS PCR assay as compared to the reference standard was 96.0% (95% CI 90.1% to 98.4%), specificity 98.6% (95% CI 95.8% to 99.5%), positive predictive value (PPV) 96.9% (95% CI 91.4% to 99.0%) and negative predictive value (NPV) of 98.1% (95% CI 95.2% to 99.2%). For conventional swab cultures, sensitivity was 96.0% (95% CI 90.1% to 98.4%), specificity 100% (95% CI 98.2% to 100%), PPV 100%, (95% CI 96.1% to 100%) and NPV 98.1% (95% CI 95.2% to 99.3%)
In this retrospective study, the GAS PCR assay appeared to perform as well as conventional throat swab culture, the current standard of practice. Since the GAS PCR assay, including DNA extraction, can be performed in approximately 1 hour, prospective studies of this assay are warranted to evaluate the clinical impact of the assay on management of patients with pharyngitis.
PCR; rapid; internally-controlled; LCGreen; Group A Streptococcus; pharyngitis; flocked swab
Individuals with advanced chronic kidney disease (CKD) and end stage renal disease (ESRD) have high total plasma homocysteine (tHcy) levels, which may be a risk factor for cognitive impairment. Whether treatment with high dose B-vitamins to reduce high tHcy levels improves cognition in persons with kidney disease is unknown.
Randomized controlled trial.
Setting & Participants
A substudy of 659 patients (mean age 67.3 ± 11.7 years) who participated in a randomized, double-blind, clinical trial, 5 years in duration, conducted in 36 US Department of Veterans Affairs medical centers, of the effect on all-cause mortality of vitamin-induced lowering of plasma tHcy. 236 (35.8%) were treated by dialysis (ESRD) and 423 (64.2%) had a Cockcroft-Gault estimated creatinine clearance ≤ 30 ml/min (advanced CKD). All had high tHcy levels (≥15 μmol/L) at baseline. Cognitive assessments began during the follow up period of the main trial, 3 years after treatment began; participants were subsequently retested one year later to assess cognitive change.
Daily high dose B-vitamin capsule (40 mg of folic acid, 100 mg of vitamin B6, and 2 mg of vitamin B12) or placebo.
Cognitive function at initial assessment and one year later.
The Telephone Interview of Cognitive Status – modified, supplemented with attention, working memory and executive function tests.
Initial cognitive function was impaired in approximately 19% of patients, regardless of treatment assignment (vitamin or placebo) or kidney disease status (advanced CKD or ESRD). Treatment reduced tHcy levels by 26.7%. Unadjusted and adjusted analyses showed that treatment did not improve initial cognitive outcomes or affect subsequent cognitive status one year later.
Cognitive assessments began after treatment was initiated; cognitive assessment was limited.
Treatment with high daily doses of B-vitamins, which reduced tHcy levels, did not affect cognitive outcomes in patients with advanced CKD and ESRD.
Cognition; Kidney Disease; Homocysteine; Clinical Trial
The endoplasmic reticulum (ER) in S. cerevisae is largely divided between perinuclear and cortical compartments. Yeast Nvj1 localizes exclusively to small patches on the perinuclear ER, where it interacts with Vac8 in the vacuole membrane to form nucleus-vacuole (NV) junctions. Three regions of Nvj1 mediate the biogenesis of NV junctions. A membrane-spanning domain targets the protein to the ER. The C-terminus binds Vac8 in the vacuole membrane, which induces the clustering of both proteins into NV junctions. The luminal N-terminus is required for strict perinuclear localization. 3D cryo-electron tomography reveals that Nvj1 clamps the separation between the two nuclear membranes to half the width of bulk nuclear envelope. The N-terminus contains a hydrophobic sequence bracketed by basic residues that resembles outer mitochondrial membrane signal-anchors. The hydrophobic sequence can be scrambled or reversed without affecting function. Mutations that reduce the hydrophobicity of the core sequence, or affect the distribution of basic residues, cause mislocalization to the cortical ER. We conclude that the N-terminus of Nvj1 is a retention sequence that bridges the perinuclear lumen and inserts into the inner nuclear membrane.
We compared the performance of flocked swabs to that of traditional swabs for culture of beta-hemolytic streptococci in children with pharyngitis. Sensitivity was higher for flocked swabs, but this did not reach statistical significance. We conclude that flocked swabs can be used in place of traditional swabs for diagnosis of streptococcal pharyngitis.
Gout recently passed rheumatoid arthritis to become the most common inflammatory arthritis in the United States (US). However, epidemiologic studies indicate that the quality of gout management is suboptimal owing to both patient and physician issues. Only three options for urate-lowering therapy are currently available in the US: allopurinol, probenecid, and recently, febuxostat. Probenecid is generally safe except for the occurrence of urolithiasis, but is only effective for the subset of patients with better kidney function. Allopurinol use is limited due to its side effects, potential toxicity of uncertain magnitude in patients with renal disease, and failure to achieve targeted serum urate levels. In part this failure may be due to the necessity for it to be titrated for optimal therapeutic effect. Febuxostat is a new medication that may offer several advantages and can be given as an alternative to allopurinol. We review the basic biology and clinical performance of febuxostat, and consider the potential utility of this agent in comparison to the older, better-established gout therapeutics.
allopurinol; gout suppressants; nephrolithiasis; uric acid; urolithiasis
Klebsiella pneumoniae isolates from three patients admitted to the Ottawa Hospital, a 1,040-bed teaching hospital, were found to contain the plasmid-borne K. pneumoniae carbapenemase (KPC)-producing bla gene (blaKPC). There was evidence of person-to-person transmission for two patients. Screening of 186 clinical isolates revealed no additional blaKPC-containing isolates.
We have established that two homologous nucleoporins, Nup170p and Nup157p, play an essential role in the formation of nuclear pore complexes (NPCs) in Saccharomyces cerevisiae. By regulating their synthesis, we showed that the loss of these nucleoporins triggers a decrease in NPCs caused by a halt in new NPC assembly. Preexisting NPCs are ultimately lost by dilution as cells grow, causing the inhibition of nuclear transport and the loss of viability. Significantly, the loss of Nup170p/Nup157p had distinct effects on the assembly of different architectural components of the NPC. Nucleoporins (nups) positioned on the cytoplasmic face of the NPC rapidly accumulated in cytoplasmic foci. These nup complexes could be recruited into new NPCs after reinitiation of Nup170p synthesis, and may represent a physiological intermediate. Loss of Nup170p/Nup157p also caused core and nucleoplasmically positioned nups to accumulate in NPC-like structures adjacent to the inner nuclear membrane, which suggests that these nucleoporins are required for formation of the pore membrane and the incorporation of cytoplasmic nups into forming NPCs.
Due to the shortage of organs, living donor acceptance criteria are becoming less stringent. An accurate determination of the glomerular filtration rate (GFR) is critical in the evaluation of living kidney donors and a value exceeding 80ml/min per 1.73m2 is usually considered suitable. To improve strategies for kidney donor screening, an understanding of factors that affect GFR is needed. Here we studied the relationships between donor GFR measured by 125I-iothalamate clearances (mGFR) and age, gender, race, and decade of care in living kidney donors evaluated at the Cleveland Clinic from 1972 to 2005. We report the normal reference ranges for 1057 prospective donors (56% female, 11% African American). Females had slightly higher mGFR than males after adjustment for body surface area, but there were no differences due to race. The lower limit of normal for donors (5th percentile) was less than 80 ml/min per 1.73m2 for females over age 45 and for males over age 40. We found a significant doubling in the rate of GFR decline in donors over age 45 as compared to younger donors. The age of the donors and body mass index increased over time, but their mGFR, adjusted for body surface area, significantly declined by 1.49±0.61 ml/min per 1.73m2 per decade of testing. Our study shows that age and gender are important factors determining normal GFR in living kidney donors.
age; gender; GFR; living donor; MDRD; race
Currently, the general paediatrics examination administered by the Royal College of Physicians and Surgeons of Canada is offered annually in the spring. Controversy exists regarding its seasonal timing. Assessing the views of residents anticipating the examination is relevant to examination administrators.
To determine paediatric residents’ opinions regarding the timing of the general paediatrics examination.
A survey was electronically distributed to all resident members of the Canadian Paediatric Society with an e-mail reminder after one week. Responses were collected independently, forwarded to the authors and summarized using descriptive statistics. Multinomial regression identified predictors of examination preference and estimated prediction value.
One hundred sixty-four of 585 surveys (28%) were returned. Common preferences included ‘spring of 4th year’ (42%) and ‘fall of 4th year’ (22%). Respondents intending four years of general paediatrics demonstrated a 55% preference for ‘spring of 4th year’ and 11% for ‘fall of 4th year’, compared with preferences of 29% and 34%, respectively, for respondents intending three years of general paediatrics followed by subspecialty training (P<0.001). This was confirmed by multinomial regression (OR 2.49; P<0.0001). Increasing training year was associated with increasing support for examination in the fall relative to the spring of 4th year (OR 1.37; P=0.019).
Residents’ preferences for the timing of the examination are varied, with ‘spring of 4th year’ being most preferred. Residents demonstrated stronger support for ‘fall of 4th year’ with increasing years of training, and if planning to pursue subspecialty training after three years of general paediatrics.
Certification examination; Paediatrics; Postgraduate medical education; Residency training; Survey; Timing
Increasing genomic instability is associated with aging in eukaryotes, but the connection between genomic instability and natural variation in life span is unknown. We have quantified chronological life span and loss-of-heterozygosity (LOH) in 11 natural isolates of Saccharomyces cerevisiae. We show that genomic instability increases and mitotic asymmetry breaks down during chronological aging. The age-dependent increase of genomic instability generally lags behind the drop of viability and this delay accounts for ∼50% of the observed natural variation of replicative life span in these yeast isolates. We conclude that the abilities of yeast strains to tolerate genomic instability co-vary with their replicative life spans. To the best of our knowledge, this is the first quantitative evidence that demonstrates a link between genomic instability and natural variation in life span.
TSC13 is required for the biosynthesis of very-long-chain fatty acids (VLCFAs) in yeast. Tsc13p is a polytopic endoplasmic reticulum (ER) membrane protein that accumulates at nucleus–vacuole (NV) junctions, which are formed through Velcro-like interactions between Nvj1p in the perinuclear ER and Vac8p on the vacuole membrane. NV junctions mediate piecemeal microautophagy of the nucleus (PMN), during which bleb-like portions of the nucleus are extruded into invaginations of the vacuole membrane and degraded in the vacuole lumen. We report that Tsc13p is sequestered into NV junctions from the peripheral ER through Vac8p-independent interactions with Nvj1p. During nutrient limitation, Tsc13p is incorporated into PMN vesicles in an Nvj1p-dependent manner. The lumenal diameters of PMN blebs and vesicles are significantly reduced in tsc13-1 and tsc13-1 elo3-Δ mutant cells. PMN structures are also smaller in cells treated with cerulenin, an inhibitor of de novo fatty acid synthesis and elongation. The targeting of Tsc13p-GFP into NV junctions is perturbed by cerulenin, suggesting that its binding to Nvj1p depends on the availability of fatty acid substrates. These results indicate that Nvj1p retains and compartmentalizes Tsc13p at NV junctions and that VLCFAs contribute to the normal biogenesis of trilaminar PMN structures in yeast.
Nucleus-vacuole (NV) junctions in Saccharomyces cerevisiae are formed through specific interactions between Vac8p on the vacuole membrane and Nvj1p in the nuclear envelope. Herein, we report that NV junctions in yeast promote piecemeal microautophagy of the nucleus (PMN). During PMN, teardrop-like blebs are pinched from the nucleus, released into the vacuole lumen, and degraded by soluble hydrolases. PMN occurs in rapidly dividing cells but is induced to higher levels by carbon and nitrogen starvation and is under the control of the Tor kinase nutrient-sensing pathway. Confocal and biochemical assays demonstrate that Nvj1p is degraded in a PMN-dependent manner. PMN occurs normally in apg7-Δ cells and is, therefore, not dependent on macroautophagy. Transmission electron microscopy reveals that portions of the granular nucleolus are often sequestered into PMN structures. These results introduce a novel mode of selective microautophagy that targets nonessential components of the yeast nucleus for degradation and recycling in the vacuole.
The nuclear pore complex (NPC) is a permeable sieve that can dilate to facilitate the bidirectional translocation of a wide size range of receptor-cargo complexes. The binding of receptors to FG nucleoporin docking sites triggers channel gating by an unknown mechanism. Previously, we used deoxyglucose and chilling treatments to implicate Nup170p and Nup188p in the control of NPC sieving in Saccharomyces cerevisiae. Here, we report that aliphatic alcohols increase the permeability of wild-type and nup170Δ NPCs. In conjunction with increases in permeability, aliphatic alcohols, deoxyglucose, and chilling trigger the reversible dissociation of several nucleoporins from nup170Δ NPCs. These results are consistent with the hypothesis that NPC gating occurs when molecular latches composed of FG repeats and structural nucleoporins dissociate.
The vertebrate nuclear pore complex (NPC) harbors an ∼10-nm diameter diffusion channel that is large enough to admit 50-kD polypeptides. We have analyzed the permeability properties of the Saccharomyces cerevisiae nuclear envelope (NE) using import (NLS) and export (NES) signal-containing green fluorescent protein (GFP) reporters. Compared with wild-type, passive export rates of a classical karyopherin/importin (Kap) Kap60p/Kap95p-targeted NLS-GFP reporter (cNLS-GFP) were significantly faster in nup188-Δ and nup170-Δ cells. Similar results were obtained using two other NLS-GFP reporters, containing either the Kap104p-targeted Nab2p NLS (rgNLS) or the Kap121p-targeted Pho4p NLS (pNLS). Elevated levels of Hsp70 stimulated cNLS-GFP import, but had no effect on the import of rgNLS-GFP. Thus, the role of Hsp70 in NLS-directed import may be NLS- or targeting pathway-specific. Equilibrium sieving limits for the diffusion channel were assessed in vivo using NES-GFP reporters of 36–126 kD and were found to be greater than wild-type in nup188-Δ and nup170-Δ cells. We propose that Nup170p and Nup188p are involved in establishing the functional resting diameter of the NPC's central transport channel.
nuclear pore complex; import/export signals; green fluorescent protein; diffusion channel; Saccharomyces cerevisiae
NIP7 encodes a conserved Saccharomyces cerevisiae nucleolar protein that is required for 60S subunit biogenesis (N. I. T. Zanchin, P. Roberts, A. DeSilva, F. Sherman, and D. S. Goldfarb, Mol. Cell. Biol. 17:5001–5015, 1997). Rrp43p and a second essential protein, Nop8p, were identified in a two-hybrid screen as Nip7p-interacting proteins. Biochemical evidence for an interaction was provided by the copurification on immunoglobulin G-Sepharose of Nip7p with protein A-tagged Rrp43p and Nop8p. Cells depleted of Nop8p contained reduced levels of free 60S ribosomes and polysomes and accumulated half-mer polysomes. Nop8p-depleted cells also accumulated 35S pre-rRNA and an aberrant 23S pre-rRNA. Nop8p-depleted cells failed to accumulate either 25S or 27S rRNA, although they did synthesize significant levels of 18S rRNA. These results indicate that 27S or 25S rRNA is degraded in Nop8p-depleted cells after the section containing 18S rRNA is removed. Nip7p-depleted cells exhibited the same defects as Nop8p-depleted cells, except that they accumulated 27S precursors. Rrp43p is a component of the exosome, a complex of 3′-to-5′ exonucleases whose subunits have been implicated in 5.8S rRNA processing and mRNA turnover. Whereas both green fluorescent protein (GFP)-Nop8p and GFP-Nip7p localized to nucleoli, GFP-Rrp43p localized throughout the nucleus and to a lesser extent in the cytoplasm. Distinct pools of Rrp43p may interact both with the exosome and with Nip7p, possibly both in the nucleus and in the cytoplasm, to catalyze analogous reactions in the multistep process of 60S ribosome biogenesis and mRNA turnover.