To clarify the mechanism of detecting the motion of contrast modulations, the spatiotemporal properties of direction discrimination for contrast motion were examined. The stimulus was a microbalanced random stimulus [Chubb and Sperling (1988) Journal of the Optical Society of America A 5, 1986-2007], termed random-window kinematogram (RWK), a shifting random checkerboard pattern in which each check was either a patch of random dots (uncorrelated between frames) or a patch of uniform gray having the mean luminance of the random dots. The effect of exposure duration (ED) on RWK discrimination could be described as stimulus onset asynchrony (SOA) dependency when EDs of the first and second frames were the same, but the performance was better than predicted from SOA when the first ED was short while the second was long. RWK could be seen at longer inter-stimulus intervals than random-dot kinematogram (RDK) having similar stimulus parameters (e.g. check size, effective contrast). Incoherent motion (e.g. reversed phi) could be seen for RWK. Maximum displacement limit (Dmax) for RWK was comparable to that of RDK, but it increased in proportion to check size, while Dmax for RDK did not. These results suggest that the contrast motion mechanism extracts motion locally, and involves a correlation-type motion extraction stage similar to the luminance motion mechanism. In addition, the spatial ranges of the contrast motion detectors are comparable to those of the luminance motion detectors, but their temporal range is larger. The contrast motion mechanism is more scale-invariant than the luminance motion mechanism.

Contrast Sensitivity↗

PubMedDate not supplied

Wave form decomposition of 'giant SEP' and its computer model for scalp topography.

By using the decomposition technique developed by ourselves to investigate the scalp topography of evoked potentials, a computer model for the scalp topography of giant SEPs was computed from 5 patients with progressive myoclonic epilepsy and was compared with those obtained from 6 normal subjects. Components of giant SEPs were similar to those of normal SEPs with respect to various parameters, although the former were much larger than the latter. An experimental enlargement of some of the early cortical components of the normal SEP model gave rise to a wave form closely resembling that of the giant SEP. These findings support our previous conclusion, derived from study of the scalp topography of the original SEP wave form, that the giant SEP results from a pathological enhancement of certain early cortical components of the normal SEP. The underlying neuronal hyperexcitability seems to involve more than one subunit of the sensorimotor cortex.

Adolescent↗

PubMedDate not supplied

Characteristics of auditory P300 in children: application of single trial analysis.

As, especially in children, cognitive function might vary from one stimulus to the other, even when the same target stimuli are presented in the oddball paradigm, we applied the single trial analysis adopting discrete Fourier transformation followed by inverse discrete Fourier transformation to the auditory P300 for the first time in children. In 9 children, age 9-13 years, a positive peak was clearly identified in approximately a quarter of the processed single sweep responses to target stimuli (single sweep P300), whereas it was observed less frequently for non-target stimuli. In 2 children of age 6 years, it was difficult to discriminate single sweep P300 from background EEG activities even in the processed data. As for the former group, the detection ratio of P300 in single sweep target responses ranged from 10.0 to 40.0%, and its mean latency and amplitude ranged from 311 to 348 ms and from 31.7 to 41.5 microV, respectively. There was a significant correlation between average data and single sweep data in terms of the P300 latency. However, the amplitude of P300 in the average data bore no relation to the detection ratio, mean amplitude or variability of latency among single sweep P300s. As compared with adult data previously reported, the detection ratio of single sweep P300 was lower and the P300 amplitude was higher in childhood. P300 in children, at least past puberty, can be analyzed by using the single trial method, which is expected to provide more information about the development of human higher brain functions, especially cognitive function.

Adolescent↗

PubMedDate not supplied

Increased bone formation by intermittent parathyroid hormone administration is due to the stimulation of proliferation and differentiation of osteoprogenitor cells in bone marrow.

In order to examine the mechanism of the anabolic effect of parathyroid hormone (PTH) on bone formation, human PTH(1-34) [hPTH(1-34)] (30 micrograms/kg) was injected subcutaneously to 9-week-old rats 5 times a week for 1 or 3 weeks. Trabecular bone volume (BV/TV) in the tibial metaphysis was not significantly different between the PTH- and vehicle-treated groups, but the parameters related to bone formation, including osteoid surface (OS/BS), mineralizing surface (MS/BS), mineral apposition rate (MAR), and bone formation rate (BFR/BS), were significantly increased as early as 1 week after PTH treatment. And the parameters related to bone resorption including eroded surface (ES/BS) and osteoclast number (N.Oc/BS) were also significantly increased as early as 1 week after PTH treatment. Treatment with PTH for 1 week induced no significant increase in bone mineral density at the femoral metaphysis, whereas the same treatment for 3 weeks induced a significant increase. When bone marrow cells isolated from femora and tibiae of either PTH- or vehicle-treated rats were cultured at a high density (2 x 10(7) cells/one well of 24-multiwell plate), cellular alkaline phosphatase (ALP) activity was significantly increased in the cells isolated from PTH-treated rats compared with vehicle-treated rats. When bone marrow cells were cultured at a low density (4 x 10(6) cells/a one well of 6-multiwell plate) to generate colonies (colony forming unit-fibroblastic, CFU-F), PTH induced apparent increases in both the total number of CFU-F and the number of ALP-positive CFU-F.(ABSTRACT TRUNCATED AT 250 WORDS)

Alkaline Phosphatase↗

PubMedDate not supplied

The Miami experience with almost 100 multivisceral transplants.

We report our experience with 98 patients who received primary multivisceral transplantations. Three eras can be distinguished based on the evolution of technique, immunosuppression, and monitoring: August 1994 to December 1997 (first era); January 1998 to December 2000 (second era); and January 2001 to present (third era). Sixteen patients were transplanted during the first era, 18 during the second era, and 64 during the third era. Fifty-three patients are alive with a median follow-up of 37.5 months (range: 1 to 116 months). The leading cause of mortality was infection (n = 17), followed by rejection (n = 6). Seven patients required retransplantation and five of them subsequently died. The estimated 3-year survival was 25% +/- 11% for era 1; 44% +/- 12% for era 2; and 58% +/- 7% for era 3. Additionally, 45.3% (29/64) of patients in the third era never developed rejection versus 23.5% (8/34) of patients in the first two eras combined. The percentage of patients who developed a moderate or severe rejection was significantly less in the third era compared with the first two eras combined, 31.6% (20/64) versus 67.6% (23/34). A comparison of the hazard rate of developing severe rejection showed a protective effect of the multivisceral graft (P = .0001). In conclusion, multivisceral transplantation is indicated for patients with short bowel syndrome and extended abdominal catastrophies. Evolution in surgical techniques, immunosuppression, and monitoring have improved patient survival, which is now similar to that of other complex solid organ transplants.

Cause of Death↗

PubMedDate not supplied

An association of lower serum citrulline levels within 30 days of acute rejection in patients following small intestine transplantation.

INTRODUCTION: In a prospective protocol we studied whether serum citrulline level within 30 days of an acute rejection was predictive of the episode. METHODS: An acute rejection episode was defined as the date of occurrence of any biopsy-proven rejection in which treatment was initiated until two successive biopsies showed no further rejection. We compared the mean citrulline level based on values determined within 30 days of the start of an acute rejection episode with the mean citrulline level measured on the same patient during a rejection-free period. Serum citrulline measurements were available immediately prior to the occurrence of rejection for 22 patients who experienced 37 episodes. RESULTS: For the 12 episodes of mild rejection, the mean serum citrulline level +/- SE (standard error) was 15.0 + 2.3 micromol/L prior to rejection and 18.8 +/- 2.4 micromol/L during the rejection-free periods. A paired t test of the mean differences was not significant (P = 17). For the 25 episodes of moderate or severe rejection, the mean serum citrulline level was 12.4 +/- 1.1 micromol/L before rejection and 18.8 +/- 2.0 micromol/L during the rejection-free periods. A paired t test of the mean difference was statistically significant (P = .002). CONCLUSIONS: Although further study of citrulline as a marker for the early detection of acute rejection episodes is needed, our hope is that its use will help to prevent some of these early episodes from evolving into full-blown moderate or severe grades of rejection.

Acute Disease↗

PubMedDate not supplied

International grading scheme for acute rejection in small bowel transplantation: implementation and experience at the University of Miami.

In 2003, an international collection of pathologists and clinicians proposed a unified grading system for acute cellular rejection in endoscopically derived small intestine allograft biopsies. This grading system was implemented at the University of Miami over the past 2 years and the results are presented herein. A total of 1136 small bowel allograft biopsies with sufficient tissue for analysis were obtained from 123 hospitalized, clinic, and referral patients. The overall most common diagnosis assessing all time periods was grade IND (40%), and grade 1 rejection or greater was present in 19% percent of biopsies. A suspected vascular component to the acute rejection as identified by specific mucosal vascular changes was present in 6% of cases. Clinical decision making was very consistent with different grades. Our experience has confirmed that this new grading system is reliable and identifies clinical subsets of patients that can receive different therapy. We recommend that this international grading system be implemented for acute cellular rejection in bowel allografts as a means to standardize pathological assessment of alloimmune-induced graft injury, which will allow comparisons between different centers and clinical trials.

Florida↗

PubMedDate not supplied

CD55 and CD59 deficiency in transplant patient populations: possible association with paroxysmal nocturnal hemoglobinuria-like symptoms in Campath-treated patients.

Campath-1H therapy is directed to CD52, a small mw protein that has a glycosylphosphatidylinositol (GPI) anchor, which has a conventional structure similar to other GPI anchors such as CD55 and CD59. Paroxysmal nocturnal hemoglobinuria (PNH) results when cells have a somatic defect in the synthesis of GPI anchors and lack CD55 and CD59, as well as CD52. Several patients treated with Campath developed PNH-like symptoms with hemolysis and thrombosis. These patients were followed after therapy by measurement of peripheral CD55 and CD59 levels and showed an increased number of cells deficient in the expression of these molecules. Thereafter we instituted a screening program for the presence of CD55/59 levels in all pretransplant patients. Our results show that 17.3% of all pretransplant samples contained abnormal (9.7% of samples) or slightly abnormal (7.6% of samples) levels of granulocytes deficient in CD55 or CD59. This high prevalence of CD55/59 deficiency in Campath-treated patients with PNH-like symptoms suggests that a lack of these molecules (including CD52) could predispose to a complication of this immunosuppressive therapy.

Alemtuzumab↗

PubMedDate not supplied

Mucosal fibrosis in intestinal transplant biopsies correlates positively with the development of chronic rejection.

Endoscopic biopsies of intestinal allografts are limited to the superficial layers of the bowel. We investigated whether the presence of mucosal fibrosis in graft biopsies was indicative of chronic allograft rejection. We examined graft biopsies of 182 intestinal transplant recipients for the presence of mucosal fibrosis. Kaplan-Meier analysis showed that within 5 years posttransplantation 33% of intestinal transplant patients had graft biopsies positive for mucosal fibrosis. Although the presence of mucosal fibrosis did not affect patient or graft survival, patients with this lesion were at higher risk of developing chronic allograft enteropathy.

Adult↗

PubMedDate not supplied

Intestinal transplantation with alemtuzumab (Campath-1H) induction for adult patients.

BACKGROUND: Alemtuzumab (Campath-1H [C1H]) is a humanized monoclonal antibody directed against the CD 52 antigen that is present on the surface of T cells, B cells, natural killer cells and monocytes. We studied its application in intestinal transplantation. METHODS: This is a retrospective review of adult patients who underwent intestinal transplantation between December 1994 and May 2005. Group 1: non-C1H group (n = 39); group 2: C1H group (n = 37). C1H was administered as an induction immunosuppression in four doses (0.3 mg/kg), or in two doses (30 mg/kg). Tacrolimus levels were maintained at low level (5-10 ng/dL). No maintenance steroids were given. RESULTS: One-year survival of group 1 and group 2 patients were 57% and 70%, respectively. This difference is not statistically significant. Of 37 patients in group 2, 21 are alive. The incidence of rejection was lower in group 2 (P < .005). Average current tacrolimus level is 6.97 +/- 3.98 ng/dL. Seventeen patients (81%) are steroid free, and 15 (71%) are maintained solely on tacrolimus. There was no graft versus host disease in group 2. CONCLUSIONS: Our preliminary data suggest that C1H can provide effective immunosuppression for intestinal transplantation. Incidence of rejection was less with this regimen using low maintenance tacrolimus and minimal steroids.

Adult↗

PubMedDate not supplied

Inclusion of spleen in pediatric multivisceral transplantation.

Inclusion of the donor spleen may be beneficial for small children who receive multivisceral transplantation (MVT) because asplenia is associated with increased risk of bacterial sepsis. Beginning in 2003, the spleen was transplanted together with multivisceral transplantation in 17 children under daclizumab induction (spleen group). The results were compared to 23 children who received multivisceral transplantation without the spleen (control group) with the same immunosuppression regimen. Median age of 17 patients who received a spleen was 0.80 years (range 0.54-1.66). Platelet counts at 30 and 60 days posttransplant were significantly lower in the spleen group (average values: day 30: 399,000 vs 636,000, P = .015; day 60: 413,000 vs 622,000, P = .0056). WBC counts at 30 and 60 days posttransplant were also decreased in the spleen group but the difference was not statistically significant. Median rejection-free survival was 205 days in the spleen group and 101 days in the control group (P = NS). Median length of hospital stay was 39 days in the spleen group and 61 days in the control group. With a median follow-up of 398 days (spleen group) and 1232 days (control group), 3 of 17 (17%) in the spleen group developed graft versus host disease (GVHD), whereas 1 of 23 (4.5%) in control group did (P = NS). In one patient in each group, GVHD was fatal. No patient developed posttransplant lymphoproliferative disorder (PTLD) in the spleen group, whereas 4 of 23 (17%) in the control group developed PTLD. One-year patient survival was 84% in the spleen group and 86% in the control group. Recipients of the spleen as part of a multivisceral graft had significantly lower platelet counts. Rejection-free survival may be prolonged, but the risk of GVHD may be increased.

Antibodies, Monoclonal↗

PubMedDate not supplied

Expanded use of multivisceral transplantation for small children with concurrent liver and intestinal failure.

Fifty-five children with liver and intestinal failure have been transplanted at our center under daclizumab induction therapy since 1998. Of those, 19 received five multiviceral transplantation (MVT), 12 liver-intestine-pancreas transplants, and 2 noncomposite liver and intestine transplants (NCLIT) before 2001 (group 1). During this period, MVT was only used in children with gastric dysmotility. After 2001, we expanded the use of MVT. Therefore, 36 children in this period (group 2) received MVT except for two who received NCLIT. Median age was 1.08 in group 1 and 1.06 in group 2. Median recipient weight was 8.2 kg in group 1 and 7.5 kg in group 2. Six-month, 1-, and 2-year patient survivals were 54%, 37%, and 32% in group 1 and 94%, 91%, and 71% in group 2 (P = .00037). A statistically significant difference was observed in freedom from rejection between the two groups with group 2 being favorable (P = .0019). A statistically significant difference was observed in freedom from rejection between the two groups with group 2 being favorable (P = .0019) Four died of rejection in group 1 (21%); none died of rejection in group 2. There have been two esophago-gastrostomy strictures (one in each group) and a serious reflux of this anastomosis (group 2). Strictures were treated with balloon dilatation, and the reflux was surgically corrected. In 24 recent cases, gastro-gastric anastomosis was used in MVT with no complications to date. No pancreatic rejection was seen. Small children tolerated MVT with improved survival rates and reduced rates of rejection. Use of MVT may be considered as an alternative to liver-intestine-pancreas transplant.

Antibodies, Monoclonal↗

PubMedDate not supplied

Analysis of rejection episodes in over 100 pediatric intestinal transplant recipients.

Rejection after intestinal transplant is a significant source of morbidity and mortality. We analyzed number of rejections, severity, and duration of episodes in pediatric recipients of intestinal transplants. One hundred eighteen intestinal transplants were performed: intestine (n = 27), liver-intestine (n = 27), modified multivisceral (n = 7), and multivisceral (n = 57). A total of 186 rejections were classified: mild (n = 89), moderate (n = 70), severe (n = 27). Duration of episodes doubled for each increasing step in severity. Treatment of mild rejection was with steroids, moderate rejection was treated with OKT3, severe rejection required OKT3 and organ removal. Most rejections occurred during the first month posttransplant, with the incidence of all rejections declining after 6 months posttransplant. Intestine and liver-intestine recipients had significantly higher probability of developing severe rejections, as compared to MVT. In summary, recipients of MVT seemed to be protected from rejection as compared to intestine or liver-intestine recipients.

Adolescent↗