Tubulointerstitial nephritis due to a mutant polyomavirus BK virus strain, BKV(Cin), causing end-stage renal disease

A renal biopsy from a 36-year-old man with AIDS showed a severe tubulointerstitial nephritis with intranuclear inclusions in epithelial cells. Electron microscopy revealed the characteristic findings of a polyomavirus (PyV) infection, and immunofluorescence indicated the presence of BK virus (BKV) antigen. Inoculation of rhesus monkey kidney cell cultures both with urine and with buffy coat blood cells resulted in a cytopathic response which was subsequently confirmed to be due to BKV. Further characterization of the viral DNA from the kidney by PCR amplification and Southern blot analysis with PyV and strain-specific primers and probes indicated that the virus was closely related to the BK(Dun) strain but different in its apparent sequence arrangement. Subsequent cycle sequencing showed a dinucleotide mutation of TG-->AA which substitutes hydrophilic Gln for hydrophobic Leu in a sequence homologous to an origin DNA-binding domain of simian virus 40 T antigen. It is suggested that the mutation and a coding region rearrangement of this strain of BKV designated BKV(Cin) has the potential to alter viral DNA replication and enhance pathogenicity.

Making performance appraisals work more effectively

Today's work environment requires improved employee performance levels in order to satisfy pressures for cost containment and efficient case management techniques. Effective use of performance appraisals can play a highly valuable role in accomplishing these requirements. Design and use of an active appraisal system is discussed in this article.

Effects of subchronic exposure to cadmium chloride on endocrine and metabolic functions in rainbow trout Oncorhynchus mykiss

Adult and juvenile rainbow trout, Oncorhynchus mykiss, were exposed for 30 days to CdCl2 in water (10 and 25 micrograms Cd/L for adults, and 1 and 5 micrograms Cd/L for juveniles) to investigate effects of subchronic exposures to Cd on the hypothalamo-pituitary-interrenal and the hypothalamo-pituitary-thyroid axis, and on metabolic status. liver size and glycogen content and body mass gain were significantly reduced in the exposed adult fish and similar changes were detected in the juveniles. Plasma cortisol levels increased after exposure to the lower dose but decreased at the higher dose. Plasma T3 and T4 tended to decrease in the exposed adult fish. No significant differences in plasma glucose or cholesterol levels were detected between the controls and the exposed fish, plasma calcium levels were lower in the exposed fish. The results indicate that long-term exposures to Cd at sublethal doses have adverse effects on the physiological status of the fish and that these effects are mediated partly through alterations of endocrine function.

Activation-induced NK cell death triggered by CD2 stimulation

Both T cells and natural killer (NK) cells express CD2, the target of an alternative activation pathway that induces the proliferation of both cell types. The mitogenic response to CD2 ligation requires the co-expression of CD3:TCR in T cells and FcgammaRIII in NK cells, suggesting that these receptors are involved in transducing the response initiated by CD2. The ability of FcgammaRIII to trigger the activation-induced death of IL-2-primed NK cells led us to investigate the potential for CD2 to trigger activation-induced NK cell death. Our results reveal that the same anti-CD2 monoclonal antibodies (mAb) that activate freshly isolated NK cells induce apoptosis in IL-2-primed NK cells. CD2-induced apoptosis results in chromatin condensation, DNA fragmentation and cleavage of caspase-3. Activation-induced NK cell death triggered by CD2 ligation is extremely rapid (DNA fragmentation is first observed at 90 min) and it is not inhibited by neutralizing antibodies reactive with TNF-alpha or Fas ligand. Whereas mAb reactive with distinct CD2 epitopes (i.e. T11.1, T11.2, and T11.3) are required for activation-induced T cell death, mAb reactive with a single CD2 epitope are sufficient for activation-induced NK cell death. The ability of CD2, CD16, and CD94 to induce apoptosis in IL-2-primed lymphocytes suggests that cytokine priming changes the response to a signaling cascade that is common to each of these activation receptors.

Modification of Ran GTPase-activating protein by the small ubiquitin-related modifier SUMO-1 requires Ubc9, an E2-type ubiquitin-conjugating enzyme homologue

Covalent modification of the Ran GTPase-activating protein RanGAP1 with the ubiquitin-related protein SUMO-1 promotes its association with Nup358, a component of the cytoplasmic fibrils emanating from the nuclear pore complex (1,2). In Xenopus egg extracts, Nup358 can be found in a complex with Ubc9 (3), a structural homologue of the E2-type ubiquitin-conjugating enzymes (UBCs). Here we show that a subset of the human homologue of Ubc9 (HsUbc9) colocalizes with RanGAP1 at the nuclear envelope. HsUbc9 forms thiolester conjugates with recombinant SUMO-1, but not with recombinant ubiquitin, indicating that it is functionally distinct from E2-type UBCs. Finally, HsUbc9 is required for the modification of RanGAP1 by SUMO-1. These results suggest that HsUbc9 is a component of a novel enzymatic cascade that modifies RanGAP1, and possibly other substrates, with SUMO-1.

RNA-binding protein TIAR is essential for primordial germ cell development

Primordial germ cells (PGCs) give rise to both eggs and sperm via complex maturational processes that require both cell migration and proliferation. However, little is known about the genes controlling gamete formation during the early stages of PGC development. Although several mutations are known to severely reduce the number of PGCs reaching and populating the genital ridges, the molecular identity of only two of these genes is known: the c-kit receptor protein tyrosine kinase and the c-kit ligand (the steel factor). Herein, we report that mutant mice lacking TIAR, an RNA recognition motif/ribonucleoprotein-type RNA-binding protein highly expressed in PGCs, fail to develop spermatogonia or oogonia. This developmental defect is a consequence of reduced survival of PGCs that migrate to the genital ridge around embryonic day 11.5 (E11.5). The numbers of PGCs populating the genital ridge in TIAR-deficient embryos are severely reduced compared to wild-type embryos by E11.5 and in the mutants PGCs are completely absent at E13.5. Furthermore, TIAR-deficient embryonic stem cells do not proliferate in the absence of exogenous leukemia inhibitory factor in an in vitro methylcellulose culture assay, supporting a role for TIAR in regulating cell proliferation. Because the development of PGCs relies on the action of several growth factors, these results are consistent with a role for TIAR in the expression of a survival factor or survival factor receptor that is essential for PGC development. TIAR-deficient mice thus provide a model system to study molecular mechanisms of PGC development and possibly the basis for some forms of idiopathic infertility.

Association of phosphorylated serine/arginine (SR) splicing factors with the U1-small ribonucleoprotein (snRNP) autoantigen complex accompanies apoptotic cell death

Proteins subject to proteolysis or phosphorylation during apoptosis are commonly precipitated by autoantibodies found in the serum of patients with systemic lupus erythematosus (SLE). We screened a panel of murine monoclonal and human monospecific sera reactive with known autoantigens for their ability to selectively precipitate phosphoproteins from apoptotic Jurkat T cell lysates. Sera known to recognize the U1-small nuclear ribonucleoprotein (snRNP) complex (confirmed by their ability to precipitate U1-snRNA) selectively precipitated a phosphoprotein complex (pp54, pp42, pp34, and pp23) from apoptotic lysates. Monoclonal antibodies reactive with U1-snRNP proteins precipitated the same phosphoprotein complex from apoptotic lysates. The phosphorylation and/or recruitment of these proteins to the U1-snRNP complex is induced by multiple apoptotic stimuli (e.g., Fas ligation, gamma irradiation, or UV irradiation), and is blocked by overexpression of bcl-2. The U1-snRNP-associated phosphoprotein complex is immunoprecipitated by monoclonal antibodies reactive with serine/arginine (SR) proteins that comprise a structurally related family of splicing factors. The association of phosphorylated SR proteins with the U1-snRNP complex in cells undergoing apoptosis suggests a mechanism for regulation of alternative splicing of apoptotic effector molecules.

Alcohol, cardiovascular diseases and public health policy

Public health policy should aim to reduce the harm done by alcohol use, whilst recognizing its real and perceived benefits. The reduced risk of coronary heart disease (CHD) with the consequent reduction of mortality for some people in older age is one such benefit. The increased risk of sudden coronary death from acute alcohol intoxication is one such harm. A number of policies have been demonstrated to be effective in the reduction of the harm done by alcohol use, at least in industrialized countries. These are: enforcement of a minimum drinking age; drink-drive deterrence; enforced prevention of intoxication in public drinking places; controls on access to alcohol, including restrictions on numbers of licensed premises and hours and days of sale; and taxation policy to regulate the affordability of alcohol. Many of these strategies seem unlikely to have a direct effect on drinking relevant for reduced risk of CHD, but are likely to have a direct beneficial effect on drinking relevant for sudden coronary death. The level of alcohol consumption associated with the lowest mortality rate for a population will vary depending on patterns of ill health and causes of death. In countries with high rates of CHD the per capita level may be in the order of about three litres of absolute alcohol per year among drinking adults. In countries with low rates of CHD, the level is likely to be substantially lower. Many countries in which alcohol is readily available are consuming at a level substantially above three litres per capita of drinking adults per year and in these countries public health policy should continue to advise action to reduce per capita consumption.

Serum antibody responses of weanling mice and two-year-old children to pneumococcal-type 6A-protein conjugate vaccines of differing saccharide chain lengths

Type 6A pneumococcal polysaccharide (PS) fractions having mean lengths 2, 7, or 14 repeat units were coupled to tetanus toxoid, giving conjugates T-6A-2, T-6A-7 or T-6A-14. In weanling outbred mice, type-6A serum antibody responses were minimal to T-6A-7 but significantly higher to T-6A-2 and T-6A-14. In contrast, two-year-old humans responded increasingly to T-6A-2, T-6A-7, and T-6A-14; type 6B antibody rose, but variably. Upon challenge with 6B PS at age 3 yr, conjugate-primed children made anamnestic responses. T-6A-14, containing the longest saccharide chains (and highest saccharide:protein mass ratio) excelled in priming as well as antibody induction.

Behavioural analysis of olfactory conditioning in the moth spodoptera littoralis (Boisd.) (Lepidoptera: noctuidae)

We studied the associative learning capabilities for behaviourally relevant cues in the moth Spodoptera littoralis. The moths were trained to associate a conditioned stimulus (CS), geraniol odour, with an unconditioned stimulus (US), a sucrose solution. The occurrence of a proboscis extension reflex (PER) was tested. The PER performance during acquisition increased steadily with the number of training trials. Non-associative control procedures did not result in learning. PER conditioning was achieved when the CS was presented 1-3 s before the US. A wide range of inter-trial intervals was able to support conditioning. Males and females learned equally well. Moths could to some degree learn the CS-US association after a single trial. These results demonstrate that S. littoralis females and males have a good capability to associate an odour with a reward. The neural basis of olfactory coding in moths has been well studied; thus, the moth provides a powerful system in which to examine the neurobiology of olfactory learning.

Left ventricular function and remodeling after myocardial infarction in aging rats

Adaptations of the aging left ventricle (LV) to hemodynamic overload are functionally and structurally distinct from those of the young organism. This study describes the influence of aging on LV hemodynamics and remodeling late after myocardial infarction (MI) in Fischer 344 Brown Norway rats. In sham rats at 23 mo, LV weight, myocyte cross-sectional area (CSA), and myocardial fibrosis were increased, whereas LV dP/dt, LV relaxation, and maximal LV systolic function declined with respect to younger rats (7, 12, and 18 mo of age). Isometric myocardial function was evaluated in papillary muscles of 12- and 23-mo-old sham rats. Myocardial systolic function was decreased in older rats. To determine how aging affects LV function and remodeling after MI, rats were infarcted at 7 and 18 mo of age and were studied 5 mo later. Infarct size was similar in each group. Right ventricular weight, LV end-diastolic pressure, and volume index were increased, whereas LV dP/dt, peak cardiac index, and peak developed LV pressure declined after MI. However, there were no significant differences between young and older rats in any variable of LV systolic function or remodeling after MI. Myocyte CSA increased in younger rats after MI but was unchanged in 23-mo-old rats. After MI, myocardial fibrosis was significantly increased from baseline only in younger rats. The negative interaction of aging and MI on myocyte hypertrophy and fibrosis was highly significant. The findings indicate that baseline LV and myocradial function decline with age. In the aging rat after MI, despite limited compensatory hypertrophy and more advanced baseline myocardial fibrosis, the long-term functional and structural adaptations to MI are similar to those of the mature adult heart.

Malnutrition and microcephaly in Australian aboriginal children

OBJECTIVE

To examine the association between malnutrition and microcephaly in the first two years of life.

DESIGN

Cross-sectional study.

SETTING AND PARTICIPANTS

Royal Darwin Hospital (a tertiary referral centre); 157 of 165 previously studied Aboriginal children aged under two years who were admitted with diarrhoea between May 1990 and April 1991. Birth weight, birth length, birth head circumference, admission head circumference and admission nutritional status were examined. Nutritional status was categorised according to World Health Organization (WHO) criteria for wasting (thinness) and stunting (shortness). Microcephaly on admission was defined as a head circumference less than the second percentile on Australian reference charts. Small-for-gestational-age (SGA) and birth microcephaly were defined as being less than the tenth percentile for an Australian hospitalised population, corrected for gestational age at confinement. Low birth weight (LBW) was defined as less than 2500 g.

MAIN OUTCOME MEASURE

Microcephaly on admission.

RESULTS

Of the 157 children, 76 (48%) were wasted, 36 (23%) stunted and 37 (24%) microcephalic on admission. A total of 26 (17%) children had been of LBW, 17 (11%) SGA and 21 (13%) microcephalic at birth. On univariate analysis, microcephaly on admission was associated with wasting (crude odds ratio [OR], 3.91; 95% confidence interval [CI], 1.6-9.7; P < 0.005), but not stunting. There were no significant associations between microcephaly on admission and LBW, being SGA, microcephaly at birth, age or sex. With multivariate analysis, birth head circumference was significantly associated with microcephaly on admission (adjusted OR, 3.62; 95% CI, 1.28-10.23; P < 0.05), as was wasting (adjusted OR, 4.38; 95% CI, 1.88-10.20; P < 0.001).

CONCLUSIONS

Wasting was significantly associated with microcephaly, independent of intrauterine growth retardation (as measured by being SGA) and LBW. As malnutrition in critical periods of both intra- and extrauterine development may have irreversible effects on intellectual potential and behaviour, the emphasis on improved nutrition must begin during pregnancy, and should continue in infancy and early childhood.

CD94 ligation induces apoptosis in a subset of IL-2-stimulated NK cells

CD94 (Kp43) is a member of the human C-type lectin superfamily encoding type II membrane glycoproteins expressed on NK cells and a subset of T cells. Ligation of CD94 has been shown to either potentiate or inhibit NK cell proliferation and cytolytic effector function. Here we show that CD94 ligation triggers apoptosis in IL-2-primed NK cells. Evidence for CD94-induced apoptosis includes: 1) chromatin condensation as measured by increased fluorescence of Hoechst dye, 2) induction of DNA fragmentation, and 3) characteristic morphology by transmission electron microscopy. IL-2 priming (at least 12 h) is required for activation-induced NK cell death triggered by CD94. Activation-induced NK cell death triggered by CD94 ligation is extremely rapid (DNA fragmentation is first observed at 120 min). Unlike activation-induced T cell death, it is not inhibited by neutralizing Abs reactive with TNF-alpha or Fas ligand. Our results suggest that CD94 may play a role in the elimination of activated NK cells during the transition from the innate to the Ag-specific immune response.

CD94 ligation induces apoptosis in a subset of IL-2-stimulated NK cells

CD94 (Kp43) is a member of the human C-type lectin superfamily encoding type II membrane glycoproteins expressed on NK cells and a subset of T cells. Ligation of CD94 has been shown to either potentiate or inhibit NK cell proliferation and cytolytic effector function. Here we show that CD94 ligation triggers apoptosis in IL-2-primed NK cells. Evidence for CD94-induced apoptosis includes: 1) chromatin condensation as measured by increased fluorescence of Hoechst dye, 2) induction of DNA fragmentation, and 3) characteristic morphology by transmission electron microscopy. IL-2 priming (at least 12 h) is required for activation-induced NK cell death triggered by CD94. Activation-induced NK cell death triggered by CD94 ligation is extremely rapid (DNA fragmentation is first observed at 120 min). Unlike activation-induced T cell death, it is not inhibited by neutralizing Abs reactive with TNF-alpha or Fas ligand. Our results suggest that CD94 may play a role in the elimination of activated NK cells during the transition from the innate to the Ag-specific immune response.

Efficacy of metered-dose inhaler administration of albuterol in intubated infants

STUDY OBJECTIVE

To compare the safety and efficacy of metered-dose inhaler (MDI) albuterol to nebulized (NEB) albuterol administration.

DESIGN

A randomized, triple-blinded, crossover study.

SETTING

A pediatric ICU in a tertiary care children's hospital.

PATIENTS

Eleven intubated infants with bronchiolitis.

INTERVENTIONS

Subjects received four puffs of MDI albuterol (360 microg) and 3 mL of NEB saline solution placebo or 0.3 mL of NEB albuterol (1.5 mg) and MDI saline solution placebo. Each set of albuterol and saline solution placebo was administered after direct attachment of delivery device to the endotracheal tube and bag-valve system. Subjects received the opposite sequence 4 h after the initial sequence. The second sequence was given first the next day, and the first sequence was administered 4 h later.

MEASUREMENTS AND RESULTS

Respiratory system compliance and resistance were measured at baseline and 30 min, 1 h, 2 h, and 4 h after each set of placebo and albuterol. There was an appreciable improvement in compliance and resistance for up to 2 h following both methods of administration. However, the degree of improvement was not significantly different (p>0.05) between the two methods. Neither method caused a significant change in resistance when measured at 4 h after albuterol/placebo administration. No evidence of toxicity was detected.

CONCLUSIONS

MDI-administered albuterol is as safe and efficacious as nebulized-administered albuterol in intubated infants with bronchiolitis. Generalizability of these results is limited by differences in drug delivery with different brands of nebulizers and spacers and sites of attachment.

Standardization of an opsonophagocytic assay for the measurement of functional antibody activity against Streptococcus pneumoniae using differentiated HL-60 cells

Host protection against pneumococcal disease i primarily mediated by phagocytosis. We developed and standardized an opsonophagocytic assay using HL-60 cells (human promyelocytic leukemia cells). Fifty-five serum samples were analyzed for the presence of functional antibody against seven pneumococcal serogroups or serotypes (4, 6B, 9V, 14, 18C, 19F, and 23F) by using differentiated HL-60 cells (granulocytes) and peripheral blood leukocytes (PBLs). Six of the 55 serum samples were from unvaccinated adult volunteers, 31 serum samples were from adults who received one dose of the 14-valent or the 23-valent polysaccharide vaccine, and 18 serum samples were from 16-month-old infants who received four doses of an investigational 7-valent polysaccharide-protein conjugate vaccine. The results of an opsonophagocytic assay with HL-60 cells correlated highly with those of an assay with PBLs as effector cells (median r for seven serotypes = 0.87: P < 0.01). Opsonophagocytic titers were compared with the immunoglobulin G antibody concentrations determined by enzyme-linked immunosorbent assay (ELISA). The r values for serogroups or serotypes 4, 6B, 9V, 14, 18C, 19F, and 23F were 0.61, 0.60, 0.67 0.90, 0.61, 0.39, and 0.57, respectively, when HL-60 cells were used as effector cells and 0.56, 0.47, 0.61, 0.90, 0.71, 0.31, and 0.62, respectively, when PBLs were used. The assay requires small amounts of serum (40 microliters per serotype), making this test suitable for assaying infant sera. Culturable cells aid in assay standardization and likely reduce donor-to-donor variability. This standardized assay, in combination with the standardized ELISA, can be used to evaluate current and developing pneumococcal vaccines, in which functional opsonophagocytic antibody activity may correlate with protection against pneumococcal disease.

Cardiovascular risk factors in homeless adults

Homelessness is a growing problem in the United States, with population numbers ranging from 300,000 to several million. This article reviews five studies that focused on identification and assessment of cardiovascular risk factors in the homeless population. A case study presents the successful outcome of a homeless male with several risk factors. Assessment and intervention by a nurse practitioner led to his re-entry into the domiciled population. Implications for clinical practice and recommendations for further research are discussed.

Management of impalpable testes: indications for abdominal exploration

Various approaches to the management of the impalpable testis in cases of cryptorchidism have been advocated. The authors' experience over the past 13 years was reviewed to try to determine an optimal approach. Of 1,305 patients with undescended testicles seen between February 1982 and December 1995, 157 boys (12.03%) had impalpable testes with 17 having bilateral impalpable testes for a total of 174 impalpable testes. A hernia sac was present in 155 impalpable testes with a testicle present in all cases. No hernia sac was found in 19 impalpable testes, five of which had no testicle present. This was confirmed by either open exploration or laparoscopy. One hundred forty-eight boys underwent groin exploration as initial treatment, 13 of these had bilateral impalpable testes. In addition to the five absent testicles with no hernia sac, one patient with a hernia sac and no testicle evident benefited from subsequent laparoscopy to identify an intraabdominal testicle. All other patients underwent routine orchidopexy or orchidectomy (one case with grossly malformed testicle). Nine boys underwent laparoscopy as initial treatment, four of these had bilateral impalpable testes. Two abnormal testicles were found and removed. Groin exploration and subsequent orchidopexy was definitive treatment in all other cases. The association of a hernia sac with an impalpable undescended testicle is very significant (P < .00001 Fisher's Exact test). The absence of a sac therefore may reflect an alternate diagnosis. When no sac is found with a testicle in the groin, this may represent an ectopic testicle. When no sac is found with no testicle, this may represent a vanishing testicle. From this experience the authors conclude that groin exploration should be the initial approach to impalpable testes. The presence of a hernia sac with an absent testicle demands further exploration; the absence of a hernia sac with an absent testicle suggests a vanishing testicle and may need no further exploration.

Team-based participation in the hiring process

In most health care settings today, effective patient service results from medical staff members working together as a high performance team. These teams evolve through the process of hiring employees who combine the necessary technical skills, knowledge, and abilities (SKAs) to perform the job and whose interpersonal attributes will add value to services provided by the team. This article promotes the concept that those who are in the best position to determine whether a job candidate will become a productive team member are, in most cases, the team members themselves. Discussion includes types of teams and degree of member involvement. For those health care professionals interested in using greater team-based participation in employment matters, specific advantages and realistic challenges are provided.

Determination of albuterol in plasma after aerosol inhalation by gas chromatography-mass spectrometry with selected-ion monitoring

Albuterol is a beta2-adrenergic agonist commonly used as a bronchodilator for the treatment of patients with asthma. We have developed an assay to determine plasma levels as low as 50 pg/ml of albuterol by gas chromatography-mass spectrometry (GC-MS). This assay utilizes isotopically labeled albuterol ([13C]albuterol) as an internal standard. In this assay albuterol and the internal standard are recovered from 1 ml of plasma using solid-phase extraction. The samples are then derivatized to trimethylsilyl ethers using N,O-bis(trimethylsilyl)trifluoro-acetamide with 1% trimethylchlorosilane. The samples are then analyzed by GC-MS with selected-ion monitoring (SIM) for the ions m/z 369.15 and 370.15. The method has been validated for a concentration range of 50-10000 pg/ml in plasma.

Cytotoxicity and apoptosis in human renal allografts: identification, distribution, and quantitation of cells with a cytotoxic granule protein GMP-17 (TIA-1) and cells with fragmented nuclear DNA

In the present study, we analyzed human renal allografts using immunohistochemical techniques to determine the site, identity, and frequency of (a) cytotoxic and apoptotic cells, as identified by staining for GMP-17 (TIA-1), a component of cytotoxic granules; and (b) DNA fragmentation in situ, as detected by the TUNEL method. In acute cellular rejection (n = 15), GMP-17+ mononuclear cells accounted for 29% +/- 12% of the infiltrating cells in the interstitium (341 +/- 164/mm2) and were significantly more concentrated in tubulitis lesions, where they amounted to 65% +/- 14% of the mononuclear cells (96 +/- 61/mm2) (p < 0.01 versus interstitium). GMP-17+ mononuclear cells were also found in sites of endothelialitis. An estimated 80% of the GMP-17+ lymphocytes expressed CD8, and 10% to 20% expressed either CD4 or the macrophage marker CD14. The latter finding led us to analyze normal peripheral blood monocytes by flow cytometry, all of which were found to contain GMP-17. NK cells and neutrophils, which are known to express GMP-17, were detected only rarely in allografts. Specimens with cyclosporine A toxicity (n = 7) or acute tubular necrosis (n = 13) showed fewer GMP-17+ cells in the interstitium (22 +/- 46/mm2 and 62 +/- 50/mm2, respectively) and tubules (2 +/- 6/mm2 and 10 +/- 10/mm2, respectively) (all p < 0.01 versus rejection). These differences were due largely to less intense mononuclear cell infiltration. In cyclosporine A toxicity, however, the percentages of GMP-17+ mononuclear cells within tubules and the interstitium were significantly lower than in rejection (p = 0.02), whereas in acute tubular necrosis significantly lower percentages were found in the tubules (p = 0.04) but not in the interstitium. Native kidneys with end-stage diabetic nephropathy (n = 5) had very low proportions of GMP-17+ cells in interstitial infiltrates (7% +/- 6%) and in tubules (11% +/- 15%), although the infiltrates were focally intense (517 +/- 355/mm2). TUNEL+ cells were found in acute cellular rejection, predominantly in areas with intense mononuclear infiltrates and also within lesions of tubulitis and endothelialitis. Although some TUNEL+ cells were intrinsic renal cells, most appeared to be infiltrating mononuclear cells, and we were able to detect CD3 in some. In areas of intense cellular infiltration, the percentages of TUNEL+ cells (range, 0.5% to 4.2%) were comparable to those seen in the rat thymus, indicating a high level of apoptosis. Overall, in the allograft samples, the numbers of GMP-17+ cells and TUNEL+ cells were significantly correlated (r = 0.79; p < 0.01). These data provide new evidence that T cell (and possibly macrophage)-mediated cytotoxicity plays an important role in acute renal allograft rejection, particularly in the case of tubular injury, and furthermore suggest that apoptosis may be a mechanism not only for graft cell destruction, but also for elimination of activated T cells in the infiltrate.

Life and death in the cytoplasm: messages from the 3' end

The cytoplasmic life of an mRNA revolves around the regulation of its localization, translation and stability. Interactions between the two ends of the mRNA may integrate translation and mRNA turnover. Regulatory elements in the region between the termination codon and poly(A) tail - the 3' untranslated region - have been identified in a wide variety of systems, as have been some of the key players with which these elements interact.