Pre-emptive pediatric kidney transplantation or not?

BACKGROUND: Kidney transplantation prior to dialysis (pre-emptive kidney transplantation, PKT) has been controversial because of the paucity of clinical evidence to clarify the risks and benefits of PKT. Several authors have confirmed a significant advantage of PKT in the treatment of patients with end-stage renal disease (ESRD). The aim of this study was to examine the characteristics of patients who received PKT or non-pre-emptive kidney transplant (NPKT). METHODS: We used a cohort of 323 consecutive kidney-transplanted children (53% boys) from Hospital da Criança Santo Antonio, Porto Alegre, Brazil, who underwent transplantation between January 2000 and December 2010. RESULTS: The main causes of ESRD were congenital anomalies of the kidney and urinary tract (CAKUT) (39%) and glomerulopathies (27.5%). The 12-, 36-, 60-, and 90-months death-censored graft survival rates were 97%, 92%, 86%, and 76%, respectively, in the PKT group, and 87%, 79%, 72%, and 65% in the NPKT group (P < .05). CONCLUSIONS: The results of this study suggest that pre-emptive transplantation is beneficial (hazard ratio = 0.37; 95% confidence interval: 0.18-0.82). The main causes of graft loss (n = 67) were recurrence of primary disease (21%), chronic allograft injury (17%), and death with a functioning graft (16%). We recommend PKT as a better choice for transplantation whenever possible to minimize ESRD morbidity and provide better long-term patient and graft survival.

Collaborative Brazilian Pediatric Renal Transplant Registry (CoBrazPed-RTx): A Report From 2004 to 2013.

BACKGROUND: The Collaborative Brazilian Pediatric Renal Transplant Registry started in 2004 as a multicenter initiative aiming to analyze, report, and share the results of pediatric kidney transplantation in Brazil. Data from all pediatric kidney transplants performed between January 2004 and December 2013 were recorded electronically and periodically updated. All patients under 18 years old from the participating centers were enrolled. Demographic data, etiology of chronic kidney disease, and patient and graft survival were analyzed. From a total of 2443 pediatric kidney transplants performed in Brazil during the study period, we report data from 1751 pediatric renal transplants performed in 13 centers enrolled in the collaborative study. Median age at transplantation was 12.4 years, and most of recipients were male (56%). The most common underlying renal etiologies were obstructive uropathy (31%) and glomerulopathy (26%). METHODS: According to donor source, 1155 (66%) of transplants were performed with deceased donors (DD). Initial immunosuppression consisted mainly of tacrolimus, mycophenolate, steroids, and induction therapy with anti-IL-2R antibodies. RESULTS: One-year graft survival (death-censored) was 93% and 90% (log rank test, P < .01), respectively, for living donor (LD) and DD. Graft losses (15%) were most frequently caused by vascular thrombosis, chronic allograft nephropathy, death with functioning kidney, acute rejection, and recurrent renal disease. Recipients of DD had 2.02 (95% confidence interval: 1.14-3.59) times the hazard of graft loss compared with those of LD (P = .015). Patient survival rates at 1 and 5 years were 98% and 97% for LD and 97% and 93% for DD, respectively. The mortality rate was 3.8%, mainly as the result of infection and cardiovascular disease. CONCLUSIONS: The results of this collaborative pediatric transplant study are comparable to international registries. Our effort has been able to maintain an exchange of information, both among the participating centers and with other international registries.

Factors predictive of outcome in severe lupus nephritis. Lupus Nephritis Collaborative Study Group.

In 1992, we published the results of a prospective, controlled trial of aggressive therapy (high-dose prednisone plus oral cyclophosphamide alone or with plasmapheresis) in 86 patients with severe lupus nephritis. During this study, remission (serum creatinine < or =1.4 mg/dL [< or =123 micromol/L] and proteinuria < or =330 mg/d of protein) in renal disease occurred in 37 patients (43%). To assess the long-term effect of remission on patient and renal survival, we now report the results of our extended follow-up of these patients. After an average of 10 years of follow-up in the 86 patients, patient survival rates at both 5 and 10 years were 95% in the group that had a remission and 69% at 5 years and 60% at 10 years in the no-remission group (P < 0.001). Renal survival rates were 94% at both 5 and 10 years in the remission group compared with 46% at 5 years and 31% at 10 years in the no-remission group (P < 0. 0001). Features predictive of remission included stable renal function after 4 weeks on therapy, category IV lesion, lower chronicity index, white race, lower urine protein excretion level at baseline, and lower baseline serum creatinine level. The features predictive of end-stage renal disease were higher baseline serum creatinine level, presence of anti-Ro antibodies, and failure to attain a remission. Thus, in patients with the most severe forms of lupus nephritis, a remission of clinical renal abnormalities is associated with dramatic improvement in long-term patient and renal survival.

Remission of nephrotic syndrome in type 1 diabetes: long-term follow-up of patients in the Captopril Study.

In 1994, we reported a 3.4 +/- 0.8 year follow-up of the eight patients who experienced remission of nephrotic syndrome during the Collaborative Study Group-sponsored, multicenter trial of captopril therapy in patients with type 1 diabetes with nephropathy (Captopril Study). Of the 409 patients randomized to treatment on the Captopril Study, 108 had nephrotic syndrome (24-hour proteinuria >/= 3.5 g of protein) at baseline. Of these 108 patients, 8 experienced remission of nephrotic syndrome (proteinuria

Exogenous surfactant treatment before and after sixteen hours of ischemia in experimental lung transplantation.

OBJECTIVE: A syngeneic, acute, double lung transplant model in the rat was used to determine the impact of exogenous surfactant treatment on graft function after prolonged cold storage. METHODS: The donor grafts were flush perfused, preserved for 16 hours, and then reperfused for 120 minutes. Untreated lungs served as controls (group I). In group II the recipient received a 200 mg/kg dose of surfactant (CuroSurf) before reperfusion. In groups III and IV, surfactant was administered before perfusion and harvesting (III, 20 mg/kg; IV, 200 mg/kg). Serial measurements of graft pulmonary vascular resistance, alveolar-arterial oxygen difference, and compliance were obtained. Final graft assessment included weight gain and histologic study. RESULTS: Repeated-measures analysis of variance showed significant improvement of graft performance in respect to compliance, alveolar-arterial oxygen difference, and pulmonary vascular resistance in donor surfactant treatment group IV (200 mg/kg) in comparison with recipient treatment (group II) and untreated controls (group I). Reducing the donor surfactant supplementation from 200 mg/kg to 20 mg/kg (group III) improved oxygenation and lung compliance as compared with untreated controls. Grafts in groups I and II had significantly more weight gain after 2 hours of reperfusion. Recipient treatment resulted in significantly more pulmonary hemorrhage in histologic sections. CONCLUSION: Donor treatment with exogenous surfactant is advantageous for preservation of graft function after extended ischemia. Positive effects may be seen with as little as 20 mg/kg of exogenous surfactant given before donor organ perfusion.

Typing of rabies virus isolates by DNA enzyme immunoassay.

BACKGROUND: Alternatives to antigenic typing are needed for epidemiologic surveys of the rabies virus associated with translocated coyotes and foxes, especially in areas where a closely related rabies virus is transmitted by striped skunks. OBJECTIVES: We developed and evaluated two enzyme based typing methods for rabies virus. The products of a reverse transcription-polymerase chain reaction (RT/PCR) of the nucleoprotein gene were hybridized to type specific probes and detected by enzyme assay after immobilization on microtiter plates. STUDY DESIGN: We tested RT/PCR products of 27 rabies isolates by two different DNA enzyme immunoassays (DEIA) and evaluated the quality of the results from the corresponding nucleotide sequence of the samples. RESULTS: Using a set of two probes, one of the DEIAs correctly identified 26/27 samples as variants of rabies virus associated with either skunks, foxes, or coyotes. The identity of one fox rabies sample was unresolved by this assay. The second DEIA correctly identified 24/27 samples as variants of rabies virus associated with either skunks, foxes, or coyotes. This assay did not resolve the identity of two fox rabies samples, and misidentified one fox rabies sample as a skunk rabies sample. CONCLUSIONS: DEIA can be used for epidemiologic studies of variants of rabies virus associated with skunks, foxes, and coyotes. Both DEIA methods were effective when typing probes recognized changes at a minimum of two nucleotide positions between variants, but only one assay method was sufficiently stringent to detect a single base pair mismatch. The inherent mutability of RNA viruses must be considered when designing and evaluating typing methods.

Influence of dextrans on lung preservation: is the molecular weight important?

BACKGROUND: The addition of dextran with a molecular weight of 40,000 Dalton in pulmonary preservation solutions has proved to be beneficial. However, dextrans of other size have not yet been investigated. Therefore, it is unclear whether dextran 40,000 represents the optimal additive for lung preservation solutions. METHOD: In a working rat heart-lung model, lung were preserved with regular Euro-Collins solution or with Euro-Collins solution containing 5% dextran of different sizes: 40,000 Dalton molecular weight; 70,000 Dalton molecular weight; 160,000 Dalton molecular weight. After 2 hours of ischemia functional (oxygenation; pulmonary vascular resistance) and structural (wet/dry-ratio, light microscopy) data were assessed and the amount of dextran in the lung tissue was measured. RESULTS: Lungs preserved with Euro-Collins solution 70,000 Dalton molecular weight or Euro-Collins solution 160,000 Dalton molecular weight exhibited superior functional and structural results when compared with Euro-Collins solution and Euro-Collins solution 40,000 Dalton molecular weight. Additionally, the least amount of dextran in the lung tissue was found in organs preserved with Euro-Collins solution 160,000 Dalton molecular weight after ischemia and reperfusion. CONCLUSIONS: Dextrans are useful additives for lung preservation solutions. However, the size of the molecules is important because dextrans of 160,000 Dalton molecular weight were superior to dextrans of lower molecular weight in our study.

Tricuspid valve regurgitation attributable to endomyocardial biopsies and rejection in heart transplantation.

In the present report the prevalence, severity, and risk factors of tricuspid valve regurgitation (TR) in 251 heart transplant recipients have been analyzed retrospectively. Tricuspid valve function was studied by color-flow Doppler echocardiogram and annual heart catheterization. The presence or severity of TR was graded on a scale from 0 (no TR) to 4 (severe). Additional postoperative data included rate of rejection, number of endomyocardial biopsies, incidence of transplant vasculopathy, and preoperative and postoperative hemodynamics. The incidence of grade 3 TR increases from 5% at 1 year to 50% at 4 years after transplantation. Multivariate analysis showed rate of rejection and donor heart weight to be significant risk factors. The ischemic intervals as well as the preoperative and postoperative pulmonary hemodynamics did not affect the severity or prevalence of TR. These results indicate that various factors appear to have an impact on the development of TR and that the prevalence might be lowered by a reduction of the number of biopsies performed and when possible, oversizing of donor hearts.

University of Wisconsin versus modified Euro-Collins solution for lung preservation.

In a canine model, the quality of lung preservation was assessed using pulmonary artery flush after prostacyclin administration with either modified Euro-Collins solution or University of Wisconsin solution. Twelve combined heterotopic heart and orthotopic left lung allotransplantations were performed after 6 hours of cold ischemia. Myocardial preservation was achieved using St. Thomas Hospital solution. Donor organs were anastomosed parallel to the recipient's heart and right lung, and the superior vena cava inflow was directed into the transplanted heart-left lung block after ligation of the recipient's superior vena cava proximal to the caval anastomosis. Postoperatively, cardiorespiratory function was evaluated separately for donor and recipient organs at an inspired oxygen fraction of 0.4 for a maximum of 12 hours. Significantly improved oxygenation and lower pulmonary vascular resistance index of the donor lung was observed in the University of Wisconsin + prostacyclin group, whereas pulmonary artery pressures showed no significant differences in between both groups. It is concluded that superior results in lung preservation can be achieved with pulmonary artery flush perfusion using University of Wisconsin solution and prostacyclin when compared with Euro-Collins solution and prostacyclin.

Biophysical properties of the gelatin-resorcin-formaldehyde/glutaraldehyde adhesive.

Refixation of dissected aortic layers with gelatin-resorcin-formaldehyde/glutaraldehyde (GRFG) adhesive represents a new option in the surgical treatment of aortic dissection. Because of its ability to reinforce the delicate structures of the acutely dissected aortic wall, GRFG has been used increasingly in recent years. However, the biomechanical properties of the adhesive are still unclear, and little is known regarding the optimal mode of its application. In an ex vivo study, aortic specimens from sheep were glued with warm (45 degrees C) adhesive under wet and dry conditions and submitted to defined degrees of compression (5 Newtons [N], 20 N). Bonded specimens were retracted to assess tensile strength and elasticity compared with two reference adhesives: cyanoacrylate gel and fibrin glue. Gelatin-resorcin-formaldehyde/glutaraldehyde and cyanoacrylate gel showed similar results at 5 N. Both provided better adhesion when applied under dry conditions (GRFG 5 N: dry, 3.5 +/- 1.6 N/cm2; wet, 1.4 +/- 1.0 N/cm2; cyanoacrylate gel 5 N: dry, 4.8 +/- 1.8 N/cm2; wet, 3.2 +/- 1.3 N/cm2). At 20 N, GRFG tensile strength was significantly increased for either condition compared with values at 5 N (GRFG 20 N: dry, 17.1 +/- 4.2 N/cm2; wet, 4.8 +/- 1.8 N/cm2). Fibrin glue demonstrated only weak adhesive properties even under dry conditions (fibrin glue 5 N: dry, 0.8 +/- 0.3 N/cm2). Gelatin-resorcin-formaldehyde/glutaraldehyde has good adhesive properties both in wet and dry tissue. Bonding capacity can be substantially increased when applied on dry surfaces and at increased pressures.

Low-dose cyclosporine therapy in triple-drug immunosuppression for heart transplant recipients.

The toxicity of long-term immunosuppressive therapy has become a major concern in long-term follow-up of heart transplant recipients. In this respect the quality of renal function is undoubtedly linked to cyclosporin A (CsA) drug levels. In cardiac transplantation, specific CsA trough levels have historically been maintained between 250 and 350 micrograms/L in many centers without direct evidence for the necessity of such high levels while using triple-drug immunosuppression. This retrospective analysis compares the incidence of acute and chronic graft rejection as well as overall mortality between groups of patients with high (250 to 350 micrograms/L) and low (150 to 250 micrograms/L) specific CsA trough levels. A total of 332 patients who underwent heart transplantation between October 1985 and October 1992 with a minimum follow-up of 30 days were included in this study (46 women and 276 men; aged, 44 +/- 12 years; mean follow-up, 1,122 +/- 777 days). Standard triple-drug immunosuppression included first-year specific CsA target trough levels of 250 to 300 micrograms/L. Patients were grouped according to their average creatinine level in the first postoperative year (group I, < 130 mumol/L, n = 234; group II, > or = 130 mumol/L, n = 98). The overall 5-year survival excluding the early 30-day mortality was 92% (group I, 216/232) and 91% (group II, 89/98) with 75% of the mortality due to chronic rejection. The rate of rejection for the entire follow-up period was similar in both groups (first year: group I, 3.2 +/- 2.6 rejection/patient/year; group II, 3.6 +/- 2.7 rejection/patient/year; p = not significant).(ABSTRACT TRUNCATED AT 250 WORDS)

Characterization of Staphylococcus intermedius from healthy dogs and cases of superficial pyoderma by DNA restriction endonuclease patterns.

In order to study the possible clonal relation of Staphyloccocus (S.) intermedius from canine superficial pyoderma and from healthy carriers, isolates from pustular swabs and from vaginal, nasal and normal skin sabs were typed using macrorestriction analysis with Sma I and pulsed-field gel electrophoresis. From the size of the resulting fragments the size of the chromosome of S. intermedius could be determined to be roughly 1500 +/- 200 kb on the average. The fingerprints were very heterogeneous though characteristically distinct from patterns of (human) S. aureus as published by others. Strains from superficial pyoderma were not found to be more similar to each other than strains from healthy carriers. Therefore it was concluded that strains from this type of skin infection probably did not belong to a certain subpopulation of S. intermedius, which might have indicated a higher virulence of these strains.

Treatment of recurrent rejection in heart transplantation: cytolytic therapy or bolus steroids?

OBJECTIVES: The treatment of recurrent rejection in heart transplant recipients has been a controversial issue for many years. The intent of this retrospective study was to perform a risk-benefit analysis between treatment strategies with bolus steroids only versus anti-thymocyte globulins (RATG; 1.5 mg/kg q 4 days). METHODS: Between 1986 and 1993, 69 of 425 patients (17 male, 52 female; mean age 44 +/- 11 years) who had more than one rejection/patient per month (rej/pt per mo) in the first 3 postoperative months were defined as recurrent rejectors. RESULTS: Repetitive methylprednisolone bolus therapy (70 mg/kg q 3 days) was given in 27 patients (group M; 1.4 +/- 0.2 rej/pt per mo) and RATG therapy for one of the rejection episodes of the 42 remaining patients (group A; 1.5 +/- 0.2 rej/pt per mo). The quality of triple drug immunosuppression in the two study groups was comparable. The rejection-free interval (RFI) following RATG treatment in group A was 21.6 +/- 10 days and 22 +/- 11 in group M. In group M, 3 of 27 patients (11%) had a rejection treatment-related infection (2 bacterial; 1 viral) versus 6 of the 42 patients of group A (14.2%; bacterial 1, viral 5). During postoperative months 3-24, 0.15 +/- 0.12 rej/pat per mo were observed in group M and 0.21 +/- 0.13 rej/pat per mo in group A (n.s.). In this 21-month period cytolytic therapy for rejection was initiated in 8 of the remaining 21 patients of group M (38%) and 15 of the remaining 37 patients of group A (40.5%). The absolute survival and the individual causes of death were not affected by the type of initial treatment of recurrent rejection. The actuarial freedom of graft atherosclerosis is comparable in the two groups with 78% in group A versus 79% in group M free of graft atherosclerosis at 3 years postoperatively. CONCLUSIONS: A comparison of cytolytic therapy versus repeated applications of bolus steroids for treatment of recurrent rejection reveals no significant difference in the long-term patient outcome with respect to the incidence of future rejection episodes and survival.

Inhaled nitric oxide and inhaled prostaglandin E1: effect on left ventricular contractility when used for treatment of experimental pulmonary hypertension.

OBJECTIVE: Pulmonary hypertension (PHT) is a life-threatening complication after isolated heart and lung transplantation. Recent work has shown that inhaled nitric oxide (NO) in combination with inhaled prostaglandin E1 (PGE1) reduce pulmonary hypertension but their influence on cardiac contractility is less well defined. METHODS: This study investigated left ventricular contractility as measured by the 'Preload Recruitable Stroke Work-Relation' (PRSW) in 24 anesthetized open chest pigs, 12 receiving in random order NO (50 ppm), PGE1 (20 microg/ml) and their combination compared to 12 controls. PHT was induced by embolization with glass beads (500 microm). Prior to induction of PHT, sonomicrometric crystals were placed on the heart to measure instantaneous cardiac dimensions. Instantaneous intraventricular pressure (micro-tip catheter) and intraventricular dimensions were recorded digitally, while intraventricular volumes were calculated from the intraventricular dimensions applying the cylindric ellipsoidal volume model for the left ventricle. PRSW was calculated from the instantaneous pressure and volume data during rapid vena caval occlusion by analysis of generated pressure-volume loops. All data were analyzed by MANOVA and corrected for heart rate (level of significance #: P < 0.05); PRSW-slope measures contractility, (PRSW-X-intercept did not change significantly). RESULTS: PRSW-change +/- SEM (in percent of initial PRSW after induction of PHT) was -14.6% +/- 4.4% versus 1.6% +/- 4.4% for NO versus Control (P = 0.004), -8.8% +/- 4.6% versus 1% +/- 3.3% (P = 0.18) for PGE1 versus Control and -5.7% +/- 4.4% versus 2.5% +/- 4.2% for NO + PGE1 versus Control (P = 0.33), respectively. In summary, application of NO 50 ppm significantly reduced left ventricular contractility while PGE1 20 microg/ml and the combination of NO and PGE1 did not. CONCLUSION: If NO is not available, the sole application of nebulized PGE1 (20 microg/ml) appears to be safe with respect to left ventricular contractility in the setting of PHT. The combination of NO and PGE1 for the treatment of pulmonary hypertension should be considered for clinical application in situations where a combination of pulmonary hypertension and decreased left ventricular function is present.

Strategies for routine biopsies in heart transplantation based on 8-year results with more than 13,000 biopsies.

The endomyocardial biopsy (EMB) in heart transplant recipients has been considered the "gold standard" for diagnosis of graft rejection (REJ). The purpose of this retrospective study is to develop long-term strategies (frequency and postoperative duration of EMB) for REJ monitoring. Between 1985 and 1992, 346 patients (mean age 44.5 years, female patients = 14%) received 382 heart grafts. For graft surveillance EMBs were performed according to a fixed schedule depending on postoperative day and the results of previous biopsies. In the first year the average number (no.) of EMBs/patient was 20 with 19% positive for REJ in the first quarter, dropping to 7% REJ/EMB by the end of the first year. The percentage of REJ/EMB declined annually from 4.7% to 4.5%, 2.2% and less than 1% after the fifth year. Individual biopsy results in the first 3 postoperative months had little predictive value. Patients with fewer than two REJ (group 1), vs patients with two or more REJ in the first 6 postoperative months (group 2), were significantly less likely to reject in the second half of the first year (group 1: 0.29 +/- 0.6 REJ/patient; group 2:0.83 +/- 1.3 REJ/patient; P < 0.001) and third postoperative year (group 1:0.12 +/- 0.33 REJ/patients; group 2:0.46 +/- 0.93 REJ/patient; P < 0.05). In conclusion, routine EMBs in the first 3 postoperative months have only limited predictive value, however the number of routine EMBs can be drastically reduced later depending on the intermediate postoperative REJ pattern.

Polymerized degradable hyaluronan--a platform for stent coating with inherent inhibitory effects on neointimal formation in a porcine coronary model.

Biodegradable hyaluronan (hyaluronic acid, HA) made insoluble by self-cross-linking in the presence of N-(3-dimethylaminopropyl)-N'-ethyl carbodiimide (EDC) has been used to cover stents. The maximum polymer-mass on a 16-mm stainless steel stent is approximately 2 mg. During manual crimping and simulated application, the loss of polymerized HA is negligible. The insoluble HA coating has an advantageous inherent antiproliferative effect regarding neointimal formation after local vessel wall injury (overstretch model) and leads to a reduced inflammatory response compared to uncoated stainless-steel stents, used as control, in undiseased pig coronary arteries, over a follow-up period of four weeks. Thus, cross-linked HA stent coating warrants further research as an interactive degradable biomaterial with an inherent inhibitory effect on neointimal formation as a possible biomatrix for local drug delivery to reduce restenosis rate.

Isolation of Mycobacterium paratuberculosis from washed bovine ova after in vitro exposure.

To establish whether Mycobacterium paratuberculosis could be cultured from Dulbecco phosphate-buffered saline solution (DPBSS) and to test 3 sampling methods, DPBSS supplemented with 2% fetal bovine serum was inoculated with M paratuberculosis at concentrations of 10(4), 10(3), 10(2), 10(1), and 10(0) colony-forming units/ml. The inoculated media was sampled after mixing, after centrifugation, and after centrifugation and decontamination with 0.75% hexadecylpyridinium chloride. The samples were inoculated onto 3 slants of Herrolds egg yolk medium supplemented with sodium pyruvate and mycobactin J and 1 slant without mycobactin J. Mycobacterium paratuberculosis was isolated following all 3 sampling methods for all concentrations. Treatment with hexadecylpyridinium chloride decreased the number of colonies isolated. To test the efficacy of a 10-step wash procedure for removing M paratuberculosis from bovine ova, washed zona pellucida intact bovine ova were incubated in DPBSS supplemented with 2% fetal bovine serum containing concentrations of 10(4), 10(3), 10(2), 10(1), and 10(0) colony-forming units of M paratuberculosis/ml for 12 hours at 22 C. Ten zona pellucida intact ova were removed from each concentration and washed by passing through 10 changes of DPBSS supplemented with 15% fetal bovine serum. The media from each wash step was inoculated onto slants of Herrolds egg yolk medium. The ova were included with the tenth wash step. Mycobacterium paratuberculosis was isolated from 1 of 10 tenth-wash steps at the 10(4) concentration and 5 of 10 tenth-wash steps at 10(3).

Isolation of Mycobacterium paratuberculosis from the uterine flush fluids of cows with clinical paratuberculosis.

Mycobacterium paratuberculosis was isolated from the uterine flush fluids obtained from 3 to 4 cows with clinical paratuberculosis. Four cows with clinical paratuberculosis were subjected to uterine lavage, using an established embryo recovery technique, and the recovered fluids were cultured for M paratuberculosis. Mycobacterium paratuberculosis has previously been demonstrated to adhere to bovine ova. Embryos within the uterus of a superovulated cow infected with M paratuberculosis could be exposed to the organism.

Estimation of the sensitivity and specificity of the agar gel immunodiffusion test for bovine leukemia virus: 1,296 cases (1982-1989).

A retrospective study of the results of 12,549 agar gel immunodiffusion tests for bovine leukemia virus, conducted on 1,296 dairy bulls over an 8-year period, was performed to estimate the sensitivity and specificity of the test. The number of tests performed on each bull ranged from 5 to 35, with a mean of 9.7 tests per bull. Bulls were categorized by their agar gel immunodiffusion test responses; 1,069 (82.5%) were noninfected and 227 (17.5%) were infected. Eighteen false-positive results were reported from the noninfected bulls. Test specificity was estimated to be 99.8%. Thirty-one false-negative results were reported from the infected bulls. Test sensitivity was estimated to be 98.5%. Fifty-six bulls had 1 or more positive responses when less than 6 months old. In 26 (46%), these results were thought to be attributable to colostral immunity.

Autoradiography of Developing Syncytia in Cotton Roots Infected with Meloidogyne incognita.

Cotton (Gossypium hirsutum) seedlings, uniformly infected with Meloidogyne incognita, were exposed for periods of 1-15 days to a nutrient solution containing tritium-labelled thymidine. Syncytium formation began with the amalgamation of cells near the nematode head, and was followed by synchronized mitoses of the nuclei which had been incorporated into a single cell. Syncytial nuclei synthesized DNA in roots harvested 3, 6, 9, 12, and 15 days after inoculation. Seedlings transferred from unlabelled to labelled nutrient solution 9 days after inoculation, and grown for 6 more days, contained some syncytial nuclei which did not become labelled. Giant-cell nuclei increased in size and, in many cases, all nuclei in one giant cell of a set showed active DNA synthesis at about the time the nematode molted to the adult stage.