Wisconsin Card Sorting Test dimensions in schizophrenia: factorial, predictive, and divergent validity

This study explored the factor structure of the Wisconsin Card Sorting Test (WCST). Scores from 197 participants with schizophrenia or schizoaffective disorder were subjected to an exploratory factor analysis that yielded three factors: Perseveration, Nonperseverative Error, and Inefficient Sorting. Comparison with two previous factor analyses revealed remarkable factorial invariance. Correlations with subject and illness characteristics, symptom dimensions, and work performance demonstrated predictive and divergent validity for the three factors. However, a representative item from each factor yielded similar correlations with very little loss of power suggesting that the factors are composed of highly redundant items. When data reduction is necessary, schizophrenia researchers are justified in using three variables: perseverative error, nonperseverative error, and failure to maintain set, to represent WCST performance.

Morphometry of in vivo human white matter association pathways with diffusion-weighted magnetic resonance imaging

The precise characterization of cortical connectivity is important for the understanding of brain morphological and functional organization. Such connectivity is conveyed by specific pathways or tracts in the white matter. Diffusion-weighted magnetic resonance imaging detects the diffusivity of water molecules in three dimensions. Diffusivity is anisotropic in oriented tissues such as fiber tracts. In the present study, we used this method to map (in terms of orientation, location, and size) the "stem" (compact portion) of the principal association, projection, and commissural white matter pathways of the human brain in vivo, in 3 normal subjects. In addition, its use in clinical neurology is illustrated in a patient with left inferior parietal lobule embolic infarction in whom a significant reduction in relative size of the stem of the left superior longitudinal fasciculus was observed. This represents an important method for the characterization of major association pathways in the living human that are not discernible by conventional magnetic resonance imaging. In the clinical domain, this method will have a potential impact on the understanding of the diseases that involve white matter such as stroke, multiple sclerosis, amyotrophic lateral sclerosis, head injury, and spinal cord injury.

Evaluating the role of Th0 and Th1 clones in autoimmune thyroid disease by use of Hu-SCID chimeras

To study the role of Th0 and Th1 cells in autoimmune thyroid disease, thyroid tissues from patients with Graves' disease (GD), Hashimoto's thyroiditis (HT), and colloid nodular disease were xenografted into SCID mice, followed by ip injection of peripheral blood mononuclear cells (PBMC), T cell lines, and T cell clones (TCC). The antigen-specific TCC reactive to TSH receptor (TSH-R), thyroid peroxidase (TPO), or thyroglobulin (Tg), and their respective peptides, were classified into Th0 (secreting IL-4 and/or IL-5 and IFN-gamma) and Th1 (secreting IFN-gamma) according to their cytokine profile. Engraftment of autologous or HLA-matched allogeneic CD4+ thyroid-specific clones with Th0 or Th1 phenotypes induced the production of total IgG and thyroid-specific autoantibodies by B cells present in xenografted thyroid tissues. TSH-R-specific clones mainly enhanced thyroid-stimulating antibodies (TSAb) production, while clones reactive to TPO and Tg increased the synthesis of TPO and Tg autoantibodies. Total IgG production, but not TSAb, was also stimulated by PBMC and TSH-R lines. TSAb correlated with the viability and hyperplasia of thyroid follicles, but not with the serum T3 levels, which were normal. Thyroid tissue viability was maintained or increased by antigen-specific Th0 clones, and decreased by Th1 clones reactive to TSH-R or TPO. Thyroid lymphocytic infiltration was variable; however, Th0 and Th1 clones from HT patients caused high degree of lymphocytic infiltration compared to the control groups. These results demonstrate for the first time that T cells clones reactive to specific epitopes of TSH-R, TPO, or Tg can generate antibody-mediated and/or cell-mediated responses in the xenografted thyroid tissue microenvironment. Such effects depend on clonal specificity, HLA class II restriction, and cytokine profile of the clone. Th0 clones reactive to TSH-R stimulate both total IgG production and TSAb in SCID mice engrafted with thyroid tissue from GD patients. Th0 and Th1 clones specific for TPO and Tg also function as helper T cells, stimulating total IgG synthesis and autoantibodies against TPO and Tg. Th1 clones may also cause tissue destruction in GD and HT.

Developmental sex differences in verbal learning

Although sex differences in verbal learning and memory have been reported in adults, much less is known about when these sex differences emerge and how they develop. In this study, 401 boys and 410 girls between the ages of 5 and 16 years were administered the California Verbal Learning Test--Children's Version. Sex differences were found at all age levels. Girls performed better than boys on all of the immediate and delayed recall trials and on the delayed recognition trial. Girls were also more likely than boys to use a semantic clustering strategy and displayed more effective long-term memory mechanisms. Boys made more intrusion errors and displayed greater vulnerability to interference between the 2 test lists. Because boys had higher mean scores on Wechsler Intelligence Scale for Children--Revised Vocabulary, the observed female superiority in verbal learning could not be attributed to sex differences in overall word knowledge.

Perseverative behavior in Alzheimer's disease and subcortical ischemic vascular dementia

Perseverative behavior has not been extensively studied in patients with dementia. In this study, perseverative behavior was elicited with the dementia version of the Graphical Sequence Test. A control group and participants with Alzheimer's disease (AD) and subcortical ischemic vascular dementia (IVD) were studied. A factor analysis revealed a 3-factor model consisting of perseverations related to semantic knowledge, motor functioning, and a third, intermediary factor. IVD participants made more total perseverations than did AD participants. Perseverations made by AD participants were correlated with deficits on tests of semantic knowledge, whereas the perseverations made by IVD participants were correlated with motor and frontal systems tests. Results are consistent with the view that perseverative behavior is hierarchically arranged in terms of specific levels of cognitive complexity and the overall pattern of cognitive deficits associated with each type of dementia.

Thyrotropin-receptor and thyroid peroxidase-specific T cell clones and their cytokine profile in autoimmune thyroid disease

We studied the cytokine profile and the immune responses to thyroid antigens of specific T cell clones (TCC) isolated from patients with Hashimoto's thyroiditis (HT) and Graves' disease (GD). Antigen-specific TCC were reactive to thyroid peroxidase (TPO), thyroglobulin (Tg) or human recombinant TSH-receptor extracellular domain (TSH-R), and/or their respective peptides. Of the 43 clones derived from HT patients, 65% were reactive to TPO, and 59% of the 32 clones derived from GD patients were reactive to TSH-R. TPO epitopes 100-119 and 625-644 were recognized by 75% of HT-derived clones, whereas TSH-R epitopes 158-176, 207-222, and 343-362/357-376 were recognized by 85% of GD-derived TCC. The TCC were classified according to their cytokine profile into T helper cell (Th)0 [secreting interleukin (IL)-4, IL-5, interferon (IFN)-gamma], Th1 (secreting IFN-gamma) and Th2 (secreting IL-4 and/or IL-5). Tumor necrosis factor-beta and IL-10 were produced by all subsets. The specific TCC were predominantly Th1-like cells in HT, and were Th0- and Th1-like cells in GD. Fifty three percent of Th0 clones were derived from GD patients and were reactive to TSH-R, whereas 50% of Th1 clones were derived from HT patients and were reactive to TPO or Tg. Most Th2 clones (82%) were reactive to TPO and were established from peripheral blood. All these clones produced IL-5, and 64% produced IL-4 and IL-10. Interestingly, IFN-gamma was highly produced by TPO- or Tg-specific clones established from HT thyroid tissue. These results confirm at the clonal level our previous studies regarding T cell epitopes on TPO and TSH-R molecules and support the concept that immunodominant T cell epitopes are located on amino acid residues 100-119 and 625-644 of TPO in HT and amino acid residues 158-176, 207-222 and 343-362/357-376 of TSH-R in GD. Our studies also demonstrate that thyroid-specific T cells can be classified into Th0, Th1, and Th2 subsets. TPO- or Tg-specific clones with Th1 phenotype appear to be involved in the pathogenesis of HT, mediating thyroid tissue destruction, whereas TSH-R clones with Th0 phenotype may induce thyroid-stimulating autoantibodies in GD.

Perseverative behavior in Alzheimer's disease and subcortical ischemic vascular dementia

Perseverative behavior has not been extensively studied in patients with dementia. In this study, perseverative behavior was elicited with the dementia version of the Graphical Sequence Test. A control group and participants with Alzheimer's disease (AD) and subcortical ischemic vascular dementia (IVD) were studied. A factor analysis revealed a 3-factor model consisting of perseverations related to semantic knowledge, motor functioning, and a third, intermediary factor. IVD participants made more total perseverations than did AD participants. Perseverations made by AD participants were correlated with deficits on tests of semantic knowledge, whereas the perseverations made by IVD participants were correlated with motor and frontal systems tests. Results are consistent with the view that perseverative behavior is hierarchically arranged in terms of specific levels of cognitive complexity and the overall pattern of cognitive deficits associated with each type of dementia.

Developmental sex differences in verbal learning

Although sex differences in verbal learning and memory have been reported in adults, much less is known about when these sex differences emerge and how they develop. In this study, 401 boys and 410 girls between the ages of 5 and 16 years were administered the California Verbal Learning Test--Children's Version. Sex differences were found at all age levels. Girls performed better than boys on all of the immediate and delayed recall trials and on the delayed recognition trial. Girls were also more likely than boys to use a semantic clustering strategy and displayed more effective long-term memory mechanisms. Boys made more intrusion errors and displayed greater vulnerability to interference between the 2 test lists. Because boys had higher mean scores on Wechsler Intelligence Scale for Children--Revised Vocabulary, the observed female superiority in verbal learning could not be attributed to sex differences in overall word knowledge.

137Cs exposure in the Marshallese populations: an assessment based on whole-body counting measurements (1989-1994)

The Marshall Islands were the site of numerous tests of nuclear weapons by the United States. From 1946 to 1958, nuclear devices were detonated at Enewetak and Bikini Atolls. Following the inadvertent contamination of the northern islands downwind of the 1954 Bravo Test, Brookhaven National Laboratory became involved in the medical care and the radiological safety of the affected populations. One important technique employed in assessing the internally deposited radionuclides is whole-body counting. To estimate current and future exposures to 137Cs, data from 1989 to 1994 were analyzed and are reported in this paper. During this period, 3,618 measurements were made for the Marshallese. The cesium body contents were assumed to result from a series of chronic intakes. Also, it was assumed that cesium activity in the body reaches a plateau that is maintained over 365 d. We estimated the annual effective dose rate for each population, derived from the recommendations of the International Commission on Radiological Protection. The average 137Cs uptake measured by the whole-body counting method varies from one population to another; it was consistent with measurements of external exposure rate. The analysis, though based on limited data, indicates that there is no statistical support for a seasonal effect on 137Cs uptake. The critical population group for cesium uptake is adult males. Within the 5-y monitoring period, all internal exposures to 137Cs were less than 0.2 mSv y(-1). Similarly, a persistent average cesium effective dose rate of 2 microSv y(-1) was determined for Majuro residents.

Assessment of plutonium exposure in the Enewetak population by urinalysis

Since 1980, the inhabitants of Enewetak Atoll have been monitored periodically by scientists from Brookhaven National Laboratory for internally deposited radioactive material. In 1989, the establishment of fission track analysis and of a protocol for shipboard collection of 24-h urine samples significantly improved our ability to assess the internal uptake of plutonium. The purpose of this report is to show the distribution of plutonium concentrations in urine collected in 1989 and 1991, and to assess the associated committed effective doses for the Enewetak population based on a long-term chronic uptake of low-level plutonium. To estimate dose, we derived the plutonium dose-per-unit-uptake coefficients based on the dosimetric system of the International Commission on Radiological Protection. Assuming a continuous uptake, an integrated Jones's plutonium urine excretion function was developed to interpret the Enewetak urine data. The Appendix shows how these values were derived. The committed effective doses were 0.2 mSv, calculated from the 1991 average plutonium content in 69 urine samples.

Response variability and timing precision of neuronal spike trains in vivo

We report that neuronal spike trains can exhibit high, stimulus-dependent temporal precision even while the trial-to-trial response variability, measured in several traditional ways, remains substantially independent of the stimulus. We show that retinal ganglion cells and neurons in the lateral geniculate nucleus (LGN) of cats in vivo display both these aspects of firing behavior, which have previously been reported to be contradictory. We develop a simple model that treats neurons as "leaky" integrate-and-fire devices and show that it, too, can exhibit both behaviors. We consider the implications of our findings for the problem of neural coding.

Fractal character of the neural spike train in the visual system of the cat

We used a variety of statistical measures to identify the point process that describes the maintained discharge of retinal ganglion cells (RGC's) and neurons in the lateral geniculate nucleus (LGN) of the cat. These measures are based on both interevent intervals and event counts and include the interevent-interval histogram, rescaled range analysis, the event-number histogram, the Fano factor, Allan factor, and the periodogram. In addition, we applied these measures to surrogate versions of the data, generated by random shuffling of the order of interevent intervals. The continuing statistics reveal 1/f-type fluctuations in the data (long-duration power-law correlation), which are not present in the shuffled data. Estimates of the fractal exponents measured for RGC- and their target LGN-spike trains are similar in value, indicating that the fractal behavior either is transmitted form one cell to the other or has a common origin. The gamma-r renewal process model, often used in the analysis of visual-neuron interevent intervals, describes certain short-term features of the RGC and LGN data reasonably well but fails to account for the long-duration correlation. We present a new model for visual-system nerve-spike firings: a gamma-r renewal process whose mean is modulated by fractal binomial noise. This fractal, doubly stochastic point process characterizes the statistical behavior of both RGC and LGN data sets remarkably well.

Measuring fatigue and other anemia-related symptoms with the Functional Assessment of Cancer Therapy (FACT) measurement system

This paper reports the development and validation of a questionnaire assessing fatigue and anemia-related concerns in people with cancer. Using the 28-item Functional Assessment of Cancer Therapy-General (FACT-G) questionnaire as a base, 20 additional questions related to the symptoms and concerns of patients with anemia were developed. Thirteen of these 20 questions dealt with fatigue, while the remaining 7 covered other concerns related to anemia. Using semi-structured interviews with 14 anemic oncology patients and 5 oncology experts, two instruments were produced: The FACT-Fatigue (FACT-F), consisting of the FACT-G plus 13 fatigue items, and the FACT-Anemia (FACT-An), consisting of the FACT-F plus 7 nonfatigue items. These measures were, in turn, tested on a second sample of 50 cancer patients with hemoglobin levels ranging from 7 to 15.9 g/dL. The 41-item FACT-F and the 48 item FACT-An scores were found to be stable (test-retest r = 0.87 for both) and internally consistent (coefficient alpha range = 0.95-0.96). The symptom-specific subscales also showed good stability (test-retest r range = 0.84-0.90), and the Fatigue subscale showed strong internal consistency (coefficient alpha range = 0.93-0.95). Internal consistency of the miscellaneous nonfatigue items was lower but acceptable (alpha range = 0.59-0.70), particularly in light of their strong relationship to patient-rated performance status and hemoglobin level. Convergent and discriminant validity testing revealed a significant positive relationship with other known measures of fatigue, a significant negative relationship with vigor, and a predicted lack of relationship with social desirability. The total scores of both scales differentiated patients by hemoglobin level (p < 0.05) and patient-rated performance status (p < 0.0001). The 13-item Fatigue subscale of the FACT-F and the 7 nonfatigue items of the FACT-An also differentiated patients by hemoglobin level (p < 0.05) and patient-rated performance status (p < or = 0.001). The FACT-F and FACT-An are useful measures of quality of life in cancer treatment, adding more focus to the problems of fatigue and anemia. The Fatigue Subscale may also stand alone as a very brief, but reliable and valid measure of fatigue.

The receptive field of the primate P retinal ganglion cell, II: Nonlinear dynamics

The receptive-field properties of retinal ganglion cells (RGCs) provide information about early visual processing. In the primate retina, P cells form the largest class of RGCs (Rodieck, 1988). A detailed exploration of the dynamics of the two subdivisions of the P-cell receptive field--the center and the surround--was undertaken. In the preceding paper (Benardete & Kaplan, 1996), the first-order responses of the center and the surround of P cells were described, which were obtained with a new technique, the multiple m-sequence stimulus (Benardete & Victor, 1994). In this paper, the investigation of P-cell responses measured as S-potentials in the lateral geniculate nucleus (LGN) is continued, and significant nonlinear, second-order responses from the center and the surround are described. These responses are quantified by fitting a mathematical model, the linear-nonlinear-linear (LNL) model (Korenberg, 1973; Korenberg & Hunter, 1986; Victor, 1988) to the data. In a second series of experiments, demonstration that steady illumination of the surround modifies the gain of the center to contrast signals (see also Kaplan & Shapley, 1989) is made. In P ON cells, increasing the steady illumination of the surround decreases the gain and speeds up the center's first-order response. In P OFF cells, increasing the steady illumination of the surround increases the gain of the center while speeding up the response. The results of both sets of experiments are related to the known anatomy and physiology of the P cell.

The receptive field of the primate P retinal ganglion cell, I: Linear dynamics

The ganglion cells of the primate retina include two major anatomical and functional classes: P cells which project to the four parvocellular layers of the lateral geniculate nucleus (LGN), and M cells which project to the two magnocellular layers. The characteristics of the P-cell receptive field are central to understanding early form and color vision processing (Kaplan et al., 1990; Schiller & Logothetis, 1990). In this and in the following paper, P-cell dynamics are systematically analyzed in terms of linear and nonlinear response properties. Stimuli that favor either the center or the surround of the receptive field were produced on a CRT and modulated with a broadband signal composed of multiple m-sequences (Benardete et al., 1992b; Benardete & Victor, 1994). The first-order responses were calculated and analyzed in this paper (part I). The findings are: (1) The first-order responses of the center and surround depend linearly on contrast. (2) The dynamics of the center and surround are well described by a bandpass filter model. The most significant difference between center and surround dynamics is a delay of approximately 8 ms in the surround response. (3) In the LGN, these responses are attenuated and delayed by an additional 1-5 ms. (4) The spatial transfer function of the P cell in response to drifting sine gratings at three temporal frequencies was measured. This independent method confirmed the delay between the (first-order) responses of the center and surround. This delay accounts for the dependence of the spatial transfer function on the frequency of stimulation.

T-cell recognition of residue 158-176 in thyrotropin receptor confers risk for development of thyroid autoimmunity in siblings in a family with Graves' disease

Twenty-two subjects in a family with Graves' Disease and 20 normal subjects unrelated to the family were examined for T-cell responses to rec h TSHR-ECD and its synthetic peptides. Seven of the family members and none of the controls responded positively to rec h TSHR-ECD. Peptide 158-176 was the only residue that showed a high percentage of response among family members, no responses in spouses, and a significant difference compared to unrelated controls. Family members under age of 6 did not differ from spouses in response to rec h TSHR-ECD or any individual peptide. Family members ages 6-12 years were significantly different from spouses in response to peptides 30-49, 158-176, and 172-186. The reactivity of adult family members including 3 Graves' patients was significantly different from spouses in response to peptides 44-62, 132-150, 158-176, and 248-263. The responses of female members of the family were higher than that of the male members and significantly different for peptide 272-291. These data suggest that recognition of peptide 158-176 may be an early event in the pathogenesis of the disease and that recognition of both 158-176 and 248-263 residues may be the cornerstone for establishment of the disease.

Tailoring of variability in the lateral geniculate nucleus of the cat

Variability is usually considered an unwanted component in a sensory signal, yet the visual system does not seem to filter out the noise. On the contrary, noise is 'tailored' to scale with the signal size. We show that this tailoring occurs in the lateral geniculate nucleus, preferentially in X-cells, which are the cells most likely to transmit pattern information. Tailoring the variability to the signal size may be the visual system's way of providing the right amount of variability for a signal of any magnitude at all times during the computation.

Pulmonary function in children treated for rhabdomyosarcoma

Chemotherapy, radiation therapy, and surgical intervention have markedly improved the survival of patients treated for rhabdomyosarcoma. Unfortunately, the therapy may have deleterious effects on the lung. Pulmonary functions tests were obtained from 17 patients treated for rhabdomyosarcoma because of our concern regarding potential pulmonary dysfunction in this group of patients who had received bleomycin, which is known to be associated with lung injury. Mean age at the time of the diagnosis of rhabdomyosarcoma was 10.1 (+/- 7.2) years (range 0.01-23.5 years). The mean age at the time of pulmonary function testing was 17.0 (+/- 7.5) years (range 5.8-34.0 years). Study patients reportedly had no pulmonary symptoms. Approximately 87% of study patients had a restrictive ventilatory impairment on pulmonary function testing as measured by total lung capacity (TLC) values less than the lower limit of normal. Approximately 70% of study patients had carbon monoxide diffusing capacity (DLCO) values less than the lower limit of normal. There were no significant differences in pulmonary function parameters when male study patients were compared to female study patients. There was a statistically significant lower forced expiratory volume in 1 second/forced vital capacity (FEV1/FVC) ratio (P=0.03) and percent predicted forced expiratory flow at 25-75% of the FVC (FEF25-75; P=0.03) in the group of patients diagnosed with rhabdomyosarcoma over 8 years of age as compared to those individuals diagnosed under 8 years of age. In addition, there were no statistically significant differences in pulmonary function when the variables of sex and age at diagnosis (as outlined above) were studied in combination. In summary, we identified a high incidence of restrictive ventilatory abnormalities in a group of individuals (predominantly children) treated for rhabdomyosarcoma as well as a significantly lower FEV1/FVC ratio and percent predicted FEF25-75 in the group of patients diagnosed with the neoplasm over 8 years of age. Individuals caring for such patients are encouraged to obtain pre- and sequential posttreatment pulmonary function tests.

Conformal technique dose escalation for prostate cancer: biochemical evidence of improved cancer control with higher doses in patients with pretreatment prostate-specific antigen > or = 10 NG/ML

PURPOSE

Conformal radiation technology results in fewer late complications and allows testing of the value of higher doses in prostate cancer.

METHODS AND MATERIALS

We report the biochemical freedom from disease (bNED) rates (bNED failure is Prostate Specific Antigen (PSA) > or = 1.5 ng/ml and rising) at 2 and 3 years for 375 consecutive patients treated with conformal technique from 66 to 79 Gy. Median follow-up was 21 months. Biochemical freedom from disease was analyzed for patients treated above and below 71 Gy as well as above and below 73 Gy. Each dose group was subdivided by pretreatment PSA level (< 10, 10-19.9, and > or = 20 ng/ml). Dose was stated to be at the center of the prostate gland.

RESULTS

There was significant improvement in bNED survival for all patients divided by a dose above or below 71 Gy (p = 0.007) and a marginal improvement above or below 73 Gy (p = 0.07). Subdividing by pretreatment PSA level showed no benefit to the PSA < 10 ng/ml group at the higher dose but there was a significant improvement at 71 and 73 Gy for pretreatment PSA 10-19.9 ng/ml (p = 0.03 and 0.05, respectively) and for pretreatment PSA > or = 20 ng/ml (p = 0.003 and 0.02, respectively).

CONCLUSIONS

Increasing dose above 71 or 73 Gy did not result in improved bNED survival for patients with pretreatment PSA < 10 ng/ml at 2 or 3 years. Further dose escalation studies may not be useful in these patients. A significant improvement in bNED survival was noted for patients with pretreatment PSA > or = 10 ng/ml treated above 71 or 73 Gy; further dose escalation studies are warranted.

The practice of surgical staging and its impact on adjuvant treatment recommendations in patients with stage I endometrial carcinoma

A survey of American gynecologic oncologists was undertaken to assess their compliance with current surgical staging criteria in patients with early endometrial carcinoma. One hundred forty-four members of the Society of Gynecologic Oncologists responded to the survey. Respondents treated an average of 22 new cases annually. Tumor grade and intraoperative determination of depth of myometrial invasion were demonstrated to influence the frequency of lymphatic dissection. In grade 1, 2, and 3 lesions, 76, 60, and 34% of responders, respectively, indicated that depth of invasion influenced their decision to perform lymphadenectomy. In addition, depth of invasion was important in determining type and extent of lymphatic resection. Further, the impact of pathologic lymph node status on postoperative adjuvant radiation therapy recommendations was evaluated for various stratifications of endometrial adenocarcinoma confined to the corpus. The greatest differences in treatment recommendations were noted in the 50-66% invasion category. For grade 1 and 2 cancers, adjuvant therapy recommendations were reduced by 23 and 16% respectively when comparing pelvic and combined therapy versus none and vaginal therapy. The effect of surgical staging data on clinical decisions is clearly evident. The knowledge of pathologically negative lymph node status reduces the recommendation for postoperative adjuvant radiotherapy in patients with adenocarcinoma otherwise confined to the uterine corpus.

Intravenous iron supplementation for the treatment of the anemia of moderate to severe chronic renal failure patients not receiving dialysis

Iron deficiency may develop in hemodialysis patients, especially when erythropoietin is given. The role of iron deficiency in the anemia of predialysis chronic renal failure (CRF), however, is much less clear. We have intravenously (IV) administered iron as ferric saccharate in a total dose of 200 mg elemental iron monthly for 5 months to 33 CRF patients who remained anemic despite oral iron supplementation and who had no laboratory signs of iron overload. None was receiving erythropoietin therapy. In 22 of the patients there was an increase in the hematocrit values by the end of the study. These patients were considered responders to intravenous iron (IV Fe) therapy. In 11 patients the iron administration was not associated with improvement of the anemia (nonresponders). Before onset of the IV Fe therapy there were no differences between the responders and nonresponders with regard to degree of anemia, serum ferritin, iron saturation, renal function, or blood pressure. One additional patient was excluded from the study because of a mild reaction during an IV test dose before the study. No worsening of kidney function and no other side effects were noted. In four patients (three responders and one nonresponder) the control of blood pressure necessitated antihypertensive drug therapy adjustment. In conclusion, IV Fe supplementation in two thirds of anemic CRF patients not receiving dialysis resulted in a significant improvement of the anemia, thus avoiding the necessity of erythropoietin or blood administration. This could be achieved by increasing the plasma ferritin levels to 200 to 400 microns/L and/or increasing the iron saturation to 25% to 35%. Intravenous ferric saccharate appears to be a safe and effective method of administering iron for the correction of anemia in CRF patients not receiving dialysis.

Intravenous ferric saccharate as an iron supplement in dialysis patients

In the present prospective study we examined the long-term effect of intravenous supplementation with ferric saccharate (IV Fe) in the treatment of the anemia of chronic dialysis patients. All patients, 64 on chronic hemodialysis (HD) and 9 on chronic ambulatory peritoneal dialysis (CAPD), were treated intravenously with this preparation in a dose of 100 mg elemental iron twice monthly. There were five groups. Group 1: 41 HD patients who were receiving erythropoietin (EPO) for at least 6 months prior to the addition of IV Fe. In this group, when IV Fe was given over 6 months, the hematocrit (Hct) increased from a mean of 28.7 to 33.7%. Over the next 6 months, the EPO dose was gradually reduced by a mean of 61.1%, but the mean Hct remained unchanged. Group 2: 11 HD patients who started IV EPO simultaneously with the IV Fe. In this group, over 6 months, the mean Hct increased from 28.1 to 34.1. Over the next 6 months, the EPO dose was gradually reduced by 75.7%, but the mean Hct remained unchanged. Group 3: 12 HD patients who received IV Fe alone for 12 months. The mean Hct increased from 30.5 to 37.9%. Group 4: 4 CAPD patients who had been receiving subcutaneous EPO for at least 6 months prior to IV Fe therapy. Over the subsequent 6 months of IV Fe, the mean Hct increased from 28.4 to 33.3%. Group 5: 5 CAPD patients not on EPO who received IV Fe for 6 months. The mean Hct increased from 27.7 to 35.6%. No adverse effects were seen in any patients throughout the study. In conclusion, adequate Fe supplementation may allow the target Hct of about 33% to be reached without, or with only very low doses of EPO. IV Fe as ferric saccharate is a new and safe form of parenteral iron therapy of the anemia of chronic dialysis patients.

Assessment of plutonium exposures in Rongelap and Utirik populations by fission track analysis of urine

A nuclear device, code-named Bravo, detonated at Bikini Atoll at 6:45 a.m. on 1 March 1954, unexpectedly released a large amount of radioactivity. Over 40 years after this incident, the study of its impact on the radiological health and environmental safety of the residents of Rongelap and Utirik Atolls continues. In 1987, researchers at Brookhaven National Laboratory established a fission track analysis (FTA) method for low-level 239Pu urinalysis. Two years later, a new shipboard protocol was developed for collecting 24-h radiologically clean urine samples. The purpose of this paper is to update information on the FTA method for measuring low-levels of plutonium, and to summarize results on the distribution of 239Pu in the populations of Rongelap and Utirik between 1981-1991. Plutonium detection levels (99% confidence level) in these samples were 2-3 microBq, which is equivalent to 0.2-0.3 mSv effective dose equivalent (EDE) to age 70 for Marshallese. The latest 1991 FTA data indicate average EDE of 0.62 mSv and 1.6 mSv for the people of Rongelap and Utirik, respectively, which both are the highest values since 1988.

Graves' disease in severe combined immunodeficient mice

Graves' disease (GD) is an autoimmune thyroid disorder involving an antibody (TSAb) directed against the TSH receptor (TSHR) producing thyroid stimulation. We have developed an animal model of GD by engrafting peripheral blood mononuclear cells or T cell lines plus autologous thyroid tissue into severe combined immunodeficient (SCID) mice. We xenografted Graves' thyroid tissue from six patients into six groups of SCID mice. Autologous PBMC and T cell lines reactive to recombinant human TSHR extracellular domain and non-TSHR lines were injected ip into the designated groups. In some of the studies, thyroid tissue was irradiated with 2000 rads before xenografting. Irradiation of xenografts induced thyroid tissue damage and release of thyroid antigens and hormones. Mice reconstituted with peripheral blood mononuclear cells or nonspecific T cell lines did not simulate GD. However, we achieved production of TSAb, elevation of serum T3, and TSAb-dependent survival and function of human Graves' thyroid tissue in SCID mice reconstituted with TSHR-specific T cell lines. We reconstituted SCID mice with PBMC and TSHR-specific T cell lines that recognized TSHR peptide 158-176. This may be in vivo evidence of the importance of peptide 158-176 as an immunodominant epitope on the TSHR extracellular domain.

Dynamics of neurons in the cat lateral geniculate nucleus: in vivo electrophysiology and computational modeling

1. We investigated the time domain transformation that thalamocortical relay cells of the cat lateral geniculate nucleus (LGN) perform on their retinal input, and used computational modeling to explore the biophysical properties that determine the dynamics of the LGN relay cells in vivo. 2. We recorded simultaneously the input (S potentials) and output (action potentials) of 50 cat LGN relay cells stimulated by drifting sinusoidal gratings of varying temporal frequency. The temporal modulation transfer functions (TMTFs) of the neurons were derived from these data. The burstiness of the LGN spike trains was also assessed using objective criteria. 3. We found that the form of the TMTF was quite variable among cells, ranging from low-pass to strongly band-pass. The optimal temporal frequency of band-pass neurons was between 2 and 8 Hz. In addition, the TMTF of some cells was nonstationary: their temporal tuning changed with time. 4. The temporal tuning of a cell was directly related to the degree of burstiness of its spike train. Tonically firing relay cells had low-pass TMTFs, whereas the most bursty neurons exhibited the most sharply band-pass transfer functions. This was also true for single cells that altered their temporal tuning: a shift to more band-pass tuning was associated with increased burstiness of the spike train, and vice versa. 5. We constructed a computer simulation of the LGN relay cell. The model was a simplified five-channel version of the thalamocortical neuron model of McCormick and Huguenard. It incorporated the quantitative kinetics of the Ca2+ T channel, as well as the Hodgkin-Huxley Na+ and K+ channels, as the only active membrane currents. To simulate the in vivo dynamics of the relay cell, the input to the model consisted of trains of synaptic potentials, recorded as S potentials in our physiological experiments. 6. When the resting membrane potential of the model neuron was relatively depolarized, the model's TMTF was low-pass, with no bursting evident in the simulated spike train. At hyperpolarized resting membrane potentials, however, the modeled TMTF was band-pass, with frequent burst discharges. Thus the biophysical model reproduced not only the range of dynamics seen in real LGN relay cells, but also the dependence of the overall dynamics on the burstiness of the spike train. However, neither of these phenomena could be simulated without the T channel. Thus the simulations demonstrated that the T-type Ca2+ channel was necessary and sufficient to explain the LGN dynamics observed in physiological experiments.(ABSTRACT TRUNCATED AT 400 WORDS)