Preemptive treatment of de novo donor-specific antibodies in lung transplant patients reduces subsequent risk of chronic lung allograft dysfunction or death

The development of donor-specific antibodies after lung transplantation is associated with downstream acute cellular rejection, antibody-mediated rejection (AMR), chronic lung allograft dysfunction (CLAD), or death. It is unknown whether preemptive (early) treatment of de novo donor-specific antibodies (dnDSAs), in the absence of clinical signs and symptoms of allograft dysfunction, reduces the risk of subsequent CLAD or death. We performed a multicenter, retrospective cohort study to determine if early treatment of dnDSAs in lung transplant patients reduces the risk of the composite endpoint of CLAD or death. In the cohort of 445 patients, 145 patients developed dnDSAs posttransplant. Thirty patients received early targeted treatment for dnDSAs in the absence of clinical signs and symptoms of AMR. Early treatment of dnDSAs was associated with a decreased risk of CLAD or death (hazard ratio, 0.36; 95% confidence interval, 0.17-0.76; P < .01). Deferring treatment until the development of clinical AMR was associated with an increased risk of CLAD or death (hazard ratio, 3.00; 95% confidence interval, 1.46-6.18; P < .01). This study suggests that early, preemptive treatment of donor-specific antibodies in lung transplant patients may reduce the subsequent risk of CLAD or death.

Donor-derived cell-free DNA accurately detects acute rejection in lung transplant patients, a multicenter cohort study

BACKGROUND

Acute rejection, which includes antibody-mediated rejection and acute cellular rejection, is a risk factor for lung allograft loss. Lung transplant patients often undergo surveillance transbronchial biopsies to detect and treat acute rejection before irreversible chronic rejection develops. Limitations of this approach include its invasiveness and high interobserver variability. We tested the performance of percent donor-derived cell-free DNA (%ddcfDNA), a non-invasive blood test, to detect acute rejection.

METHODS

This multicenter cohort study monitored 148 lung transplant subjects over a median of 19.6 months. We collected serial plasma samples contemporaneously with TBBx to measure %ddcfDNA. Clinical data was collected to adjudicate for acute rejection. The primary analysis consisted of computing the area-under-the-receiver-operating-characteristic-curve of %ddcfDNA to detect acute rejection. Secondary analysis determined %ddcfDNA rule-out thresholds for acute rejection.

RESULTS

ddcfDNA levels were high after transplant surgery and decayed logarithmically. With acute rejection, ddcfDNA levels rose six-fold higher than controls. ddcfDNA levels also correlated with severity of lung function decline and histological grading of rejection. %ddcfDNA area-under-the-receiver-operating-characteristic-curve for acute rejection, AMR, and ACR were 0.89, 0.93, and 0.83, respectively. ddcfDNA levels of <0.5% and <1.0% showed a negative predictive value of 96% and 90% for acute rejection, respectively. Histopathology detected one-third of episodes with ddcfDNA levels ≥1.0%, even though >90% of these events were coincident to clinical complications missed by histopathology.

CONCLUSIONS

This study demonstrates that %ddcfDNA reliably detects acute rejection and other clinical complications potentially missed by histopathology, lending support to its use as a non-invasive marker of allograft injury.

Does 1-minute walk test predict results of 6-minute walk test in patients with idiopathic pulmonary fibrosis?

Background

The six-minute walk test (6MWT) is a readily available tool used to evaluate functional capacity in patients with idiopathic pulmonary fibrosis (IPF). However, it is often logistically challenging to perform in the context of a busy clinical practice. We sought to investigate if the 1MWT distance (1MWD) predicts the 6MWT distance (6MWD), and if an abbreviated walk could accurately predict outcomes in IPF patients.

Methods

Baseline demographics and pulmonary function testing of IPF patients evaluated at a tertiary referral center between 2010 and 2017 were collected. 6MWT variables at baseline as well as 1 and 6 minutes were collected. Time to death, lung transplantation, or most recent follow-up was ascertained.

Results

There were 177 patients, the majority of whom (80%) were male. The mean age was 67 ± 9 years and mean FVC was 64 ± 18% predicted. Forty eight (27%) patients used oxygen supplementation during the 6MWT. The median 6MWD was 366 meters (IQR: 268-471) while the median 1MWD was 65 meters (IQR: 46-81). Stratified by the median, 89 patients were "High Walkers" based on the 6MWD ≥ 366m (HW₆) and 88 patients were "Low Walkers" (LW₆). HW₆ had a higher FVC% (70 ± 15 vs 57 ± 18, p= 0.001), higher DLCO% (45 ± 12 vs 34 ± 14, p= 0.001) and higher 1MWD (83 ± 28 vs 47 ± 16, m p= 0.001). Median transplant-free survival was better in HW₆ vs LW₆ (27 ± 16 vs 22 ± 18 months, log rank p= 0.018). There was a strong correlation between the 1MWD and the 6MWD (r= 0.91, Spearman's correlation, p < 0.0001). Also, the transplant-free survival curves stratified by 1MWD were very similar to the curves for 6MWD, showing a lower survival in the LW₁ cohort (log rank p= 0.009).

Conclusion

The 1MWD obtained during the first minute of a 6MWD shows a strong correlation to total 6MWD and retains its ability to predict transplant-free survival. 1MWT may serve as a practical substitute for the more cumbersome 6MWT. Our findings require further validation prospectively in larger cohorts of IPF patients.

Use of donor-derived-cell-free DNA as a marker of early allograft injury in primary graft dysfunction (PGD) to predict the risk of chronic lung allograft dysfunction (CLAD)

BACKGROUND

Primary graft dysfunction (PGD) is a risk factor for chronic lung allograft dysfunction (CLAD). However, the association between PGD and degree of allograft injury remains poorly defined. In this study, we leverage a novel biomarker for allograft injury, percentage donor-derived cell-free DNA (%ddcfDNA), to study the association between PGD, degree of allograft injury, and the development of CLAD.

METHODS

This prospective cohort study recruited 99 lung transplant recipients and collected plasma samples on days 1, 3, and 7 for %ddcfDNA measurements. Clinical data on day 3 was used to adjudicate for PGD. %ddcfDNA levels were compared between PGD grades. In PGD patients, %ddcfDNA was compared between those who developed CLAD and those who did not.

RESULTS

On posttransplant day 3, %ddcfDNA was higher in PGD than in non-PGD patients (median [IQR]: 12.2% [8.2, 22.0] vs 8.5% [5.6, 13.2] p = 0.01). %ddcfDNA correlated with the severity grade of PGD (r = 0.24, p = 0.02). Within the PGD group, higher levels of %ddcfDNA correlated with increased risk of developing CLAD (log OR(SE) 1.38 (0.53), p = 0.009). PGD patients who developed CLAD showed ∼2-times higher %ddcfDNA levels than patients who did not develop CLAD (median [IQR]: 22.4% [11.8, 27.6] vs 9.9% [6.7, 14.9], p = 0.007).

CONCLUSION

PGD patients demonstrated increased early posttransplant allograft injury, as measured by %ddcfDNA, in comparison to non-PGD patients, and these high %ddcfDNA levels were associated with subsequent development of CLAD. This study suggests that %ddcfDNA identifies PGD patients at greater risk of CLAD than PGD alone.

Donor-derived cell-free DNA predicts allograft failure and mortality after lung transplantation

Background

Allograft failure is common in lung-transplant recipients and leads to poor outcomes including early death. No reliable clinical tools exist to identify patients at high risk for allograft failure. This study tested the use of donor-derived cell-free DNA (%ddcfDNA) as a sensitive marker of early graft injury to predict impending allograft failure.

Methods

This multicenter, prospective cohort study enrolled 106 subjects who underwent lung transplantation and monitored them after transplantation for the development of allograft failure (defined as severe chronic lung allograft dysfunction [CLAD], retransplantation, and/or death from respiratory failure). Plasma samples were collected serially in the first three months following transplantation and assayed for %ddcfDNA by shotgun sequencing. We computed the average levels of ddcfDNA over three months for each patient (avddDNA) and determined its relationship to allograft failure using Cox-regression analysis.

Findings

avddDNA was highly variable among subjects: median values were 3·6%, 1·6% and 0·7% for the upper, middle, and low tertiles, respectively (range 0·1%–9·9%). Compared to subjects in the low and middle tertiles, those with avddDNA in the upper tertile had a 6·6-fold higher risk of developing allograft failure (95% confidence interval 1·6–19·9, p = 0·007), lower peak FEV1 values, and more frequent %ddcfDNA elevations that were not clinically detectable.

Interpretation

Lung transplant patients with early unresolving allograft injury measured via %ddcfDNA are at risk of subsequent allograft injury, which is often clinically silent, and progresses to allograft failure.

Fund

National Institutes of Health.

The importance of prediction model validation and assessment in obesity and nutrition research

Deriving statistical models to predict one variable from one or more other variables, or predictive modeling, is an important activity in obesity and nutrition research. To determine the quality of the model, it is necessary to quantify and report the predictive validity of the derived models. Conducting validation of the predictive measures provides essential information to the research community about the model. Unfortunately, many articles fail to account for the nearly inevitable reduction in predictive ability that occurs when a model derived on one data set is applied to a new data set. Under some circumstances, the predictive validity can be reduced to nearly zero. In this overview, we explain why reductions in predictive validity occur, define the metrics commonly used to estimate the predictive validity of a model (for example, coefficient of determination (R(2)), mean squared error, sensitivity, specificity, receiver operating characteristic and concordance index) and describe methods to estimate the predictive validity (for example, cross-validation, bootstrap, and adjusted and shrunken R(2)). We emphasize that methods for estimating the expected reduction in predictive ability of a model in new samples are available and this expected reduction should always be reported when new predictive models are introduced.

Energy balance measurement: when something is not better than nothing

Energy intake (EI) and physical activity energy expenditure (PAEE) are key modifiable determinants of energy balance, traditionally assessed by self-report despite its repeated demonstration of considerable inaccuracies. We argue here that it is time to move from the common view that self-reports of EI and PAEE are imperfect, but nevertheless deserving of use, to a view commensurate with the evidence that self-reports of EI and PAEE are so poor that they are wholly unacceptable for scientific research on EI and PAEE. While new strategies for objectively determining energy balance are in their infancy, it is unacceptable to use decidedly inaccurate instruments, which may misguide health-care policies, future research and clinical judgment. The scientific and medical communities should discontinue reliance on self-reported EI and PAEE. Researchers and sponsors should develop objective measures of energy balance.

Numerical study of stretched smectic-A elastomer sheets

We present a numerical study of stretching monodomain smectic-A elastomer sheets, computed using the finite element method. When stretched parallel to their smectic layer normal the smectic layers are unstable to a transition to a buckled state. We model macroscopic deformations by replacing the microscopic energy with a coarse grained effective free energy that accounts for the fine-scale layer buckling. We augment this model with a term to describe the energy of deforming buckled layers, which is necessary to reproduce the experimentally observed Poisson ratios postbuckling. We examine the spatial distribution of the microstructure phases for various stretching angles relative to the layer normal and for different length-to-width aspect ratios. When stretching parallel to the layer normal the majority of the sample forms a bidirectionally buckled microstructure, except at the clamps where a unidirectionally buckled microstructure is predicted. When stretching at small inclinations to the layer normal the phase of the sample is sensitive to the aspect ratio of the sample, with the bidirectionally buckled phase persistent to large angles only for small aspect ratios. We relate these theoretical results to experiments on smectic-A elastomers.

Negative Poisson's ratio and semisoft elasticity of smectic-C liquid-crystal elastomers

Models of smectic-C liquid-crystal elastomers predict that they can display soft elasticity, in which the shape of the elastomer changes at no energy cost. The amplitude of the soft mode and the accompanying shears are dependent on the orientation of the layer normal and the director with respect to the stretch axis. We demonstrate that in some geometries the director is forced to rotate perpendicular to the stretch axis, causing lateral expansion of the sample-a negative Poisson's ratio. Current models do not include the effect of imperfections that must be present in the physical sample. We investigate the effect of a simple model of these imperfections on the soft modes in monodomain smectic-C elastomers in a variety of geometries. When stretching parallel to the layer normal (with imposed strain) the elastomer has a negative stiffness once the director starts to rotate. We show that this is a result of the negative Poisson's ratio in this geometry through a simple scalar model.

Determining the direction to a sound source in air using vector sound-intensity probes

This paper is concerned with probes for measuring vector sound intensity in air using the minimum number of sound-pressure sensors. The probes consist of an arrangement of four small microphones at the vertices of a regular tetrahedron. They are connected to a digital signal processor, which determines the sound-intensity vector, using the cross-spectral formulation based on finite-difference approximations. Determining the direction of a sound source is an obvious application. To do this accurately the probes should be omnidirectional. This implies that the microphones in the probe have to be omnidirectional and to have the same response. Results in the paper show that the direction of a sound source can be determined with an accuracy of a few degrees. Two types of probes are described. One measures the sound-intensity vector in three-dimensional space. The other measures the vector in a half space such as would occur above the ground or in front of a wall.

Preventing glycaemic relapse in recently controlled type 2 diabetes patients: a randomised controlled trial

AIMS/HYPOTHESIS

After achieving glycaemic control, many type 2 diabetic patients relapse to clinically significant levels of hyperglycaemia. We sought to determine the optimal frequency of telephone contact by nurse practitioners that was necessary to prevent glycaemic relapse.

METHODS

This parallel, randomised controlled trial ran from June 2002 to February 2006 at an academic medical centre, studying 164 type 2 diabetic patients who had recently achieved glycaemic control. Participants were randomly assigned by sequential, concealed, computer-generated allocation to a 2 year maintenance strategy consisting of: (1) routine follow-up (n = 54); (2) routine follow-up and quarterly telephone contact (n = 55); or (3) routine follow-up and monthly telephone contact (n = 55). Blinding was not possible. The primary outcome was cumulative incidence of glycaemic relapse, defined as an increase in HbA(1c) of > or =1%; all participants were analysed. Cumulative incidence and prevalent proportions were compared. Weight change and hypoglycaemia were also assessed.

RESULTS

All participants randomised were included in the analyses. The study was completed by 90% of participants and intervention fidelity was high. At 24 months, the cumulative incidence of relapse was 41%. At 12 months, prevalent proportions of relapse were 20%, 14% and 15% for control, quarterly contact and monthly contact, respectively. At 24 months, they were 25%, 21% and 29%, respectively. There was no statistically significant difference in cumulative incidence or prevalent proportions of relapse among the study arms. Adverse events did not differ between study arms.

CONCLUSIONS/INTERPRETATION

This first randomised controlled trial to test an intervention to prevent glycaemic relapse found that regularly scheduled telephone contact by a nurse practitioner was no more effective than routine follow-up care in preventing glycaemic relapse.

Factors associated with balance deficits on admission to rehabilitation after traumatic brain injury: a multicenter analysis

OBJECTIVE

To evaluate how demographics, measures of injury severity, and acute care complications relate to sitting and standing balance in patients with traumatic brain injury (TBI).

DESIGN

Multicenter analysis of consecutive admissions to designated TBI Model Systems of Care (TBIMS).

SETTING

Ten National Institute for Disability and Rehabilitation Research TBI Model System centers for coordinated acute and rehabilitation care.

PARTICIPANTS

908 adults with TBI were included in the study.

MAIN OUTCOME MEASURES

Sitting and standing balance were assessed within 72 hours of admission to inpatient rehabilitation.

RESULTS

Age less than 50 years had a significant association with normal sitting and standing balance (P =.001 and.05, respectively). Measures of severity of traumatic brain injury, including admission Glasgow Coma Score, length of posttraumatic amnesia (PTA), length of coma, and acute care length of stay were each significantly related to impaired sitting and standing balance ratings (P <.01). Initial abnormalities in pupillary response had a significant relationship with impairment of sitting (P =.009) but not standing balance. Incidence of respiratory failure, pneumonia, soft tissue infections, and urinary tract infections were all related to impaired sitting balance (P <.01). Presence of intracranial hemorrhages did not have a significant relationship with either sitting or standing balance. Intracranial compression had a significant relationship with standing (P =.05) but not sitting balance. A discriminant function analysis, which included neuroradiological findings, injury severity, and medical complications, could not accurately predict impaired balance ratings.

CONCLUSIONS

This study demonstrated that rehabilitation admission balance ratings have a significant relationship with age, multiple measures of severity, and acute care medical complications after TBI. Prospective studies are indicated to evaluate the role balance at rehabilitation admission plays in the functional prognosis of patients with TBI.

Detection and characterisation of integrons in Salmonella enterica serotype enteritidis

Integrons have been widely described among the Enterobacteriaceae including strains of multi-resistant Salmonella enterica serotype Typhimurium DT104; however, information with respect to the presence of integrons among S. enterica serotype Enteritidis strains is limited. Multi-resistant isolates of Enteritidis were screened for the presence of integrons using a PCR protocol. One integron was detected in all isolates that were resistant to sulfonamide and streptomycin. Characterisation of these isolates indicated an integron which ranged in size between 1000 and 2000 bp and which harboured a gene cassette encoding the ant(3")-Ia gene specifying streptomycin and spectinomycin resistance. Further studies revealed the integrons to be located on large conjugative plasmids. This appears to be the first report of plasmid-borne integrons in Enteritidis.

Knee version associated with anterior knee pain

Version of the knee in the presence and absence of anterior knee pain was evaluated by computed tomography in this study. Version of the knee is defined as the static rotation of the tibia with respect to the femur in full knee extension. Fourteen patients in whom conservative management for anterior knee pain failed were compared with 14 volunteers with no symptoms. Computed tomography images of the femoral condyles and tibial plateau were obtained with the knee extended. The angle between the bicondylar and posterior tibial axes was measured. This angle, representing external rotation of the tibia relative to the femur, was increased significantly in patients with symptoms (7 degrees) compared with volunteers with no symptoms (1 degree). This increased knee version identifies a unique morphologic characteristic of the knee with anterior pain.

An out-of-home care system in crisis: implications for African American children in the child welfare system

An out-of-home care system that is itself in crisis lacks adequate resources to provide the services needed by families and children in distress. Increasingly, these families are composed of people of color, particularly African Americans. Using current child welfare statistics and a review of the literature, this article examines the nature of the crisis in child welfare, and how poverty and an array of social problems, as well as problems specific to the child welfare system, increase the overrepresentation of African American children and families in the out-of-home care system. Implications for child welfare practice and advocacy are also discussed.

Suboptimal progesterone production in pathologic pregnancies

Serum progesterone (P) levels were determined at the time of routine prenatal registration (227 patients) or upon presentation for evaluation of vaginal bleeding and/or abdominopelvic cramping/pain (135 patients). P associated with a normal intrauterine gestation was 24.63 +/- 4.19 (SD) ng/mL as compared with 6.29 +/- 2.43 ng/mL and 6.02 +/- 2.39 ng/mL for spontaneous abortions and ectopic gestations, respectively. Further, P differed between asymptomatic (11.92 +/- 9.61 ng/mL) and symptomatic patients (4.81 +/- 3.92 ng/mL) who were subsequently shown to have an abnormal gestation. By establishing a P cutoff point of < or = 14.2 ng/mL and < or = 10.5 ng/mL in asymptomatic and symptomatic patients, respectively, 100% screening sensitivity was reached, and therefore no abnormal gestations would escape detection in our study population. P was either in the normal or abnormal range as early as four weeks' estimated gestational age and persisted as such through the luteal-to-placental shift and up to the time of pregnancy loss or 12 weeks' estimated gestational age. Although there was no significant correlation between P and chorionic gonadotropin levels and pregnancy outcome, the binding constant for native chorionic gonadotropin was 15-52 times lower in 12 of 41 cases of spontaneous abortion but not ectopic gestation, suggesting a possible molecular basis for suboptimal P production. P is therefore an excellent adjunctive marker for prediction of early pregnancy outcome, and in some cases qualitative abnormalities in chorionic gonadotropin may dictate its production.

The relationship between health beliefs, adherence, and metabolic control of diabetes

There is evidence that an individual's health beliefs influence performance of health behaviors. The purpose of this study was to determine whether health beliefs in persons with diabetes could be modified during a clinical education program and whether the health beliefs were related to adherence to self-care instructions and metabolic control of diabetes. Health beliefs and HbA1c were measured at baseline in 189 adult outpatients with diabetes. Diabetes educators then attempted to modify health beliefs that were not conducive to positive health behaviors. Following education, some health beliefs were modified in a positive direction. Modest, but statistically significant increases in perceived severity of diabetes, perceived ability to carry out recommended behaviors, and perceived benefits of treatment were observed. Although HbA1c improved significantly in a subgroup of patients, this improvement could not be directly associated with any health belief or with self-reported adherence by the measures used in this study.

Dropout and relapse during diabetes care

OBJECTIVE

To determine factors associated with dropout and relapse during chronic diabetes care.

RESEARCH DESIGN AND METHODS

Private practice outpatient treatment-education program for adult diabetes was surveyed. Retrospective analysis was done, involving 422 patients for up to 3 yr.

RESULTS

Of the patients in the study, 12% dropped out after the initial visit, and 33% of the residual cohort dropped out during each subsequent 6-mo period. Factors associated with dropout included distance from home to clinic > 100 miles, lack of insulin treatment, and cigarette smoking. In patients who remained in follow-up, a significant decrease in HbA1C occurred during the first 6 mo, but 40% of the patients relapsed between 6 and 12 mo. Frequency of relapse declined as time passed. Relapse was more frequent in women.

CONCLUSIONS

Dropout from treatment and relapse after temporary improvement account for a substantial amount of uncontrolled diabetes, and overcoming the obstacles of dropout and relapse has potential for significant improvement in diabetes care.

Ubiquitin, PGP 9.5 and dense body formation in trimethyltin intoxication: differential neuronal responses to chemically induced cell damage

Ubiquitin in normal cells may be important in degrading or transferring short-lived or aberrant proteins to lysosomal dense bodies. To examine its role in degrading proteins produced by a chemical insult, changes in the distribution of ubiquitin and the carboxy-terminal hydrolase, PGP 9.5, have been studied in rat hippocampal neurons and cerebellar Purkinje cells in trimethyltin intoxication. Here tubulovesicular dense bodies (TVBs) form from 12h onwards associated with vacuolation of the Golgi apparatus. Striking accumulations of lysosomal dense bodies follow in hippocampal pyramidal cells but not in cerebellar Purkinje cells; many of the hippocampal neurons later die, while the Purkinje cells generally survive. Ubiquitin immunoreactivity was diffusely increased in hippocampal pyramidal and Purkinje cells 6 h after dosing. By 12 h both diffuse and granular ubiquitin immunoreactivity was present that intensified over 24 and 48 h. Both by light and electron microscopy TVBs showed ubiquitin immunoreactivity, but dense bodies in hippocampal perikarya did not stain with an anti-ubiquitin antibody. PGP 9.5 immunoreactivity was not altered in hippocampal cells at any time, while Purkinje and Golgi cell dendrites and perikarya showed intensified labelling at 3 h that reached a peak of 12 h. At 48 h Western blot analysis of hippocampal homogenates showed significant increases in high molecular weight (HMW) ubiquitin conjugates, while cerebellar homogenates showed an increase in ubiquitin-histone conjugates. Northern blot analyses showed no change in ubiquitin or PGP9.5 gene expression in hippocampus or cerebellum. These findings suggest that the material in the TVBs in hippocampal cells is not being degraded by the ubiquitin system but passes ubiquitinated into the lysosomal system, while material in Purkinje cell TVBs is degraded by the ubiquitin system, suggesting it may have a different composition in each type of neuron.

A comparison of the acute toxicity, neuropathology, and electrophysiology of N,N-diethyl-m-toluamide and N,N-dimethyl-2,2-diphenylacetamide in rats

The insect repellent DEET and the structurally related herbicide diphenamid both cause ataxia associated with a spongiform myelinopathy largely confined to the cerebellar roof nuclei. This local myelinopathy was accompanied by the formation of neuronal cytoplasmic clefts and was produced by a single dose of 1 to 3 g/kg N,N-diethyl-m-toluamide (DEET). These dose levels also produced a severe and often fatal prostration and clear electrophysiological signs of prolonged suppressed seizure activity. Diphenamid produced an identical myelinopathy after doses of 0.8 to 1.5 g/kg but without the severe prostration, suppressed seizures, or neuronal clefts. The effects of diphenamid were shown to be reversible over 3 to 7 days by neuropathological, motor, and auditory evoked response indices. Both compounds caused characteristic changes in auditory evoked response which may be useful in clinical diagnosis. Six other alkyl amides, two of which produce signs of CNS excitation, failed to produce myelinopathy at the maximum tolerated doses. Our findings show close parallels with a number of human cases of DEET poisoning and indicate that other amides, like diphenamid, also pose a potential hazard.

Vascular factors in the neurotoxic damage caused by 1,3-dinitrobenzene in the rat

Using a 3 x 10 mg/kg dose schedule of 1,3-dinitrobenzene (DNB) over two days in Fischer rats, we have found the following changes in vascular function and structure during the early phase of the symmetrical brain stem lesions. 1. Marked increase in cerebral blood flow generally but especially in the inferior colliculi, from 6 h after the final dose of DNB. 2. Increasing incidence of petechial haemorrhages in inferior colliculi, cerebellar roof, vestibular and superior olivary nuclei from 12 h. 3. Focal leakage of horseradish peroxidase and many sleeve-like arteriolar haemorrhages seen in vibratome sections and by scanning electron microscopy (SEM) in these regions from 12 h. 4. Periarteriolar oedema and protein leakage present in step-serial sections in these regions from 12 h, with astrocyte swelling and occasional small infarcts. These changes suggest that the vascular bed may play an important role in the pathogenesis of these lesions, perhaps in parallel with early astroglial damage. They are discussed in relation to (i) the known presence of xanthine oxidase in the vascular bed of the brain and the likelihood of "useless redox cycling' with free radical generation from this enzyme's interaction with nitroheterocyclic compounds, and (ii) the possible role of free radical damage to endothelial cells in this intoxication and in the analogous lesions of natural and experimental Wernicke's encephalopathy.

Food deprivation and hypothalamic neuropeptide gene expression: effects of strain background and the diabetes mutation

We have used a novel method to identify genes expressed in the hypothalamus which may be potentially involved in controlling food intake and energy metabolism. We assumed that food deprivation, a powerful stimulus of food intake, would stimulate the activity of neural pathways involved in feeding behavior which should be reflected in an increase in the synthesis of any relevant neuropeptide and its messenger RNA. A study of 5 neuropeptides in 5 strains of mice has identified neuropeptide Y (NPY) as a gene whose expression in the hypothalamus is controlled by nutritional status, suggesting that hypothalamic NPY neurons are a link in the neural network regulating feeding behavior and energy metabolism. In addition, we have studied the effect of the diabetes mutation on neuropeptide gene expression during fasting and refeeding. Our findings suggest that abnormal NPY and enkephalin gene expression in the hypothalamus may be two important determinants of the expression of the diabetes mutation.

Normal reticulin level in iliac bone marrow

While the level of marrow reticulin may be a factor that is used when the presence of a hematologic disorder is being considered, to our knowledge no study has graded the amount of reticulin present in normal iliac bone marrow. Grading reticulin stains of bone biopsy specimens from 100 hematologically normal patients documented that the normal amount of reticulin in the marrow is low. Twenty-seven percent of the patients had marrow reticulin grade 0 using the Bauermeister scale, 42% had grade N, 27% had grade 1, and 4% had grade 2; no patient had a Bauermeister grade 3 or 4 reticulin level. Knowledge of the normal range of reticulin is essential when the reticulin level is used as a factor in evaluating the possibility of a hematologic disorder.

Regional variations in nerve cell responses to trimethyltin intoxication in Mongolian gerbils and rats; further evidence for involvement of the Golgi apparatus

The different responses of neurons with distinctive variations in morphology and function, confirm earlier observations of the lack of uniformity in the reaction of nerve cells to trimethyltin. Thus, hippocampal pyramidal and cortical neurons in both rat and Mongolian gerbil (M. unguiculatus) show abundant lysosomal dense bodies and disorganisation of the protein-synthesising apparatus. Cerebellar Purkinje cells in gerbil, but not in rat, show striking increases in smooth membrane systems, while dense bodies are insignificant in both species; large motor-type neurons in brain stem and spinal cord in both species do not accumulate dense bodies, but their rough endoplasmic reticulum (RER) may undergo intense vacuolation with or without subsequent cell death; and by contrast, spinal ganglion cells of both species may form an excess of dense bodies and, in the gerbil, vacuolation of RER. In contrast with these varied responses to trimethyltin most neurons, large and small, in both species regularly undergo striking vacuolation of the Golgi apparatus in the earliest phase of the intoxication, a constant feature that probably reflects the site of the primary cytotoxic lesion; all other changes we consider are secondary to such damage to the Golgi apparatus, however this may come about. These observations are discussed in relation to earlier reports of the variable effects of trimethyltin and with the metabolic changes reported in trimethyltin intoxication that in general accord with these morphological conclusions.

Disabled access to information technology--a portable adaptable, multipurpose device

The technology exists to allow severely physically disabled people to have a far more independent lifestyle than many handicapped people enjoy today. To use an ever increasing range of sophisticated domestic equipment, without special modifications, an individually tailored control system and a universal accessing device are required. A portable multipurpose device allows multiply handicapped, non-speaking people a means of operating a variety of general-purpose or specialized pieces of electronic equipment at home and elsewhere, safely and independently. The device also provides a means of communication through the medium of computer-computer communication over telephone lines and will interface to a powered chair for independent mobility. Various features are provided which are not available from conventional environmental control systems. Through a specialized adjustable multipurpose switch system and a universal control device the handicapped person should be able to enjoy the independence afforded by the intelligent home of the future.

Selective degeneration of cerebellar cortical neurons caused by cycad neurotoxin, L-beta-methylaminoalanine (L-BMAA), in rats

Both the racemate and the L-form of BMAA (beta-methylaminoalanine), when injected intraperitoneally into young rats, produced acute signs of cerebellar dysfunction and degeneration of cerebellar stellate, basket, Purkinje and Golgi cells, but not granule cells. Degenerative changes were also occasionally seen in cerebellar roof nuclei which may be secondary in nature. No other changes were found in the remainder of the central nervous system. The doses of the L-form of BMAA producing these changes were from 6 to 14 mumols/g body weight, i.e. the lower and upper levels of the dose range used by Vega and Bell (1967) and equivalent to 75 and 183 mg/rat. Doses of 1 to 4 mg/g body weight of the racemate were given to young rats less than 100 g in weight, but no changes were apparent after daily doses of the racemate of 0.5 mg/g body weight. Damage to cerebellar neurons is considered to be the result of excitotoxic activity. All cells showing degeneration are GABAergic, although not all are known to possess N-methyl-D-aspartate (NMDA) receptors. The present finding of selective cerebellar neuron damage may not conflict with the earlier findings of others, but our results suggest that L-BMAA has unusual glutamate receptor binding properties.

Reversible neuronal damage in hippocampal pyramidal cells with triethyllead: the role of astrocytes

A single dose (19 mg kg-1) of triethyllead given to weanling rats produces necrosis in a small number of hippocampal pyramidal (CA3) and hilar neurons with reversible changes in the remaining neurons of this region. The sequence of events has been studied by light and electron microscopy over a period from 12 h to 14 days after dosing. Early changes resemble those previously described for trimethyltin, with the formation of characteristic tubulo-vesicular dense bodies by 12 h accompanied by vacuolation of Golgi and smooth surfaced endoplasmic reticulum (SER) elements which became generalized by 24 h. Large numbers of secondary dense bodies, formed from tubulo-vesicular dense bodies as well as from autophagosomes, were present by 48 h, whilst very little rough surfaced endoplasmic reticulum (RER) and few polyribosomes remained and vacuolation was much reduced. In those animals which did not die from seizures, the majority of hippocampal pyramidal cells were able to recover from these changes with astrocytes playing a significant role in the elimination of the dense bodies. This involved astrocytes inserting processes into the neuronal perikaryon from where the secondary dense bodies were selectively transferred into the astrocyte cytoplasm. This activity was first seen at 48 h, reached a peak at 4 days, when most CA3 neurons contained one or more astroglial intrusions and subsided soon after. The surviving neurons returned to apparent normality over the period from 3 to 7 days with a gradual return of polyribosomes. Golgi elements and RER.

1,3-Dinitrobenzene-induced encephalopathy in rats

Exposure to 1,3-dinitrobenzene (1,3-DNB) in humans induces methaemoglobinaemia, nausea and nervous symptoms. When given to conventional rats, twice-daily oral doses of 10 mg kg-1 1,3-DNB produce methaemoglobinaemia and frequently ataxia after four or five doses. In germ free rats given only a single oral dose of 20 mg kg-1, similar symptoms occur but are of more rapid onset. Light and electron microscope examinations reveal an acute thiamine deficiency-like lesion in the brain stems of both ataxic and apparently normal rats. Bilaterally symmetrical vacuolated lesions involve cerebellar roof, vestibular and superior olivary nuclei and the inferior colliculi. Frequent petechial haemorrhages are associated with these lesions, the erythrocytes usually being limited to enlarged Virchow-Robin spaces but sometimes spreading more widely. The primary cellular targets appear to be astrocytes, oligodendrocytes and vascular elements with secondary neuronal involvement. It is suggested that 1,3-DNB interferes with intracellular redox mechanisms resulting in impaired glucose oxidation.

The relationship between uncoupling of oxidative phosphorylation and neuronal necrosis within the CNS in rats dosed with trihalogenated imidazoles

The trihalogenated imidazoles, trichloroimidazole (TCI), tribromoimidazole (TBI), and triiodoimidazole (TII), are in vitro uncouplers of oxidative phosphorylation with similar activities. Although TCI and TBI are also uncouplers in vivo, some doubt exists for TII, which is much less toxic and produces atypical signs of poisoning. Dibromo- and monobromoimidazole do not uncouple oxidative phosphorylation either in vitro or in vivo. Dosing of TCI and TBI to rats resulted within 24-48 hr in neuronal necrosis within the CNS involving the vestibular nucleus, red nucleus, and outer parietal neocortex and ataxia of the hindlimbs. However, no neuronal necrosis or ataxia was observed after dosing of TII to rats, even when given at doses four times greater than for either TCI or TBI, resulting in much higher brain concentrations. Although TBI was equitoxic to rats, mice, hamsters, and gerbils, CNS damage and ataxia were observed only in the rat, even though comparable brain concentrations of TBI were found in the gerbil. Measurement of the concentration of TBI in the dissected rat brain gave no indication of localized concentrations of compound in the areas associated with neuronal damage. Doses of TBI and the classical uncoupler 3,5-dinitro-o-cresol (DNOC), matched for whole body O2 consumption, caused comparable changes in rat brain blood flow although DNOC does not cause brain damage. Changes in blood flow were not restricted to those brain areas susceptible to damage. Thus, although we were unable to completely dissociate CNS damage from uncoupling of oxidative phosphorylation produced by TBI and TCI in the rat, it is unlikely that such damage is primarily related to the uncoupling ability of these compounds.

The toxicity and neuropathology of dimethylethyltin and methyldiethyltin in rats

Triethyltin causes an increase in brain water with vacuolation of myelin sheaths, whereas trimethyltin is selectively damaging to neurons, especially of the hippocampal formations, causing chromatolysis, accumulation of cytoplasmic dense bodies and often cell death. The effects on rats of the analogues, dimethylethyltin and methyldiethyltin (oral LD50 14 mg/kg and 7.5-10.0 mg/kg respectively) are now reported. The dimethylethyl compound produces functional changes resembling those caused by trimethyltin, while the methyldiethyl compound causes responses similar to those produced by triethyltin. Structurally, however, the dimethylethyl compound, while producing marked nerve cell changes of the trimethyltin type also causes moderate vacuolation of myelin sheaths. By contrast, methyldiethyltin causes marked vacuolation of myelin sheaths of the triethyltin type and relatively minor neuronal changes of the trimethyltin type. These findings are discussed in terms of the structure-activity relationships of trialkyltin compounds.

The comparative toxicology of ethyl- and methylmercury

Neurotoxicity and renotoxicity were compared in rats given by gastric gavage five daily doses of 8.0 mg Hg/kg methyl- or ethylmercuric chloride or 9.6 mg Hg/kg ethylmercuric chloride. Three or 10 days after the last treatment day rats treated with either 8.0 or 9.6 mg Hg/kg ethylmercury had higher total or organic mercury concentrations in blood and lower concentrations in kidneys and brain than methylmercury-treated rats. In each of these tissues the inorganic mercury concentration was higher after ethyl- than after methylmercury. Weight loss relative to the expected body weight and renal damage was higher in ethylmercury-treated rats than in rats given equimolar doses of methylmercury. These effects became more severe when the dose of ethylmercury was increased by 20%. Thus in renotoxicity the renal concentration of inorganic mercury seems to be more important than the concentration of organic or total mercury. In methylmercury-treated rats damage and inorganic mercury deposits were restricted to the P2 region of the proximal tubules, while in ethylmercury-treated rats the distribution of mercury and damage was more widespread. There was little difference in the neurotoxicities of methylmercury and ethylmercury when effects on the dorsal root ganglia or coordination disorders were compared. Based on both criteria, an equimolar dose of ethylmercury was less neurotoxic than methylmercury, but a 20% increase in the dose of ethylmercury was enough to raise the sum of coordination disorder scores slightly and ganglion damage significantly above those in methylmercury-treated rats.(ABSTRACT TRUNCATED AT 250 WORDS)

The toxicity and neuropathology of 2,4,5-tribromoimidazole and its derivatives in rats

2,4,5-tribromoimidazole and its 1-n-butylcarboxylate and 1-dimethylcarbamoyl derivatives, when administered to rats, induced poisoning typical of uncouplers of oxidative phosphorylation. At 48 h rats surviving a single toxic dose of 20-60 mg/kg developed permanent incoordination of the hindlimbs in the absence of brain oedema. Neuropathologic examination of brain and spinal cord from perfused fixed rats at 24 h revealed neuronal necrosis and chromatolysis in the vestibular nucleus, the outer parietal neocortex and red nucleus. Chromatolysis and necrosis in these areas had increased at 72-96 h and were also observed in the deeper layers of the neocortex, the medial entorhinal cortex, the reticular formation, the grey matter of the spinal cord extending into the ventral horns, the dorsal, and ventral cochlear nuclei and the deep cerebellar nuclei, in decreasing order of severity. Neuronal necrosis was accompanied by an increased glial response, including neuronophagia and at 16 days with astroglial hypertrophy and hyperplasia.

Evolution of the intracellular changes in neurons caused by trimethyltin

Rats have been given a single dose of trimethyltin (10 mg/kg) and the intracellular events have been followed particularly in hippocampus, cerebral cortex, cerebellum and spinal ganglion cells. The earliest change visible occurs 12 h after this dose and is found to be dense membrane-bound bodies, probably derived from branching tubulo-vesicular smooth endoplasmic reticulum formations. These occur in close connection with rought endoplasmic reticulum and polyribosomes and appear also to have some association with the Golgi complex. At 24 h there is a general vacuolation of Golgi cisterns and SER membranes, and the membrane-bound dense body formation is greatly increased. SER abnormalities are particularly conspicuous in Purkinje cells. In spinal ganglion cells, while vacuolation of Golgi cisterns is intense, dense bodies are inconspicuous and are replaced by increased autophagosomes, often of great complexity. By 48 h vacuolation of Golgi cisterns has waned, but accumulation of dense bodies and secondary lysosomes has steadily increased. In spinal ganglion cells autophagosomes only are increased as the Golgi vacuolation declines. At later times steady increases of lysosomal dense bodies is seen generally accompanied in hippocampal pyramidal cells and dentate fascia cells by abundant cell death. The suggestion is put forward that the Golgi complex may be the seat of the critical metabolic lesion and disturbances to protein transfer and protein synthesis follow. No explanation for the selective loss of hippocampal h1-5 (CA1-CA4 except Sommer's sector) pyramidal cells and of small dentate fascia neurons can be derived from these conclusions.

The neurotoxicity of trimethyltin chloride in hamsters, gerbils and marmosets

Trimethyltin chloride (TMT) was given to Syrian hamsters, gerbils and marmosets, and the changes in the brain were studied 1 day to 7 weeks later by light and electron microscopy. Within the marmoset brain, TMT was found to be uniformly distributed, similar to that in the rat. In all three species, signs of poisoning included whole-body tremors and prostration, while death might occur in 3-4 days; in marmosets ataxia, agitation, aggression and occasional fits were also observed. Bilateral symmetrical neuronal necrosis and chromatolysis were seen in the majority, which involved the hippocampus, pyriform cortex, amygdaloid nucleus, neocortex, various brain stem nuclei and in marmosets the retina. The probably lethal dose of TMT in all three species is approximately 3 mg kg-1, while the LD50 for the rat is 12.6 mg kg-1. The lower figure is probably related to lack of binding to haemoglobin in contrast to the binding in the rat. TMT does not bind to human haemoglobin and thus the predicted lethal dose for humans may be about 3 mg kg-1 (15.1 mumol kg-1), while the dose required to produce neuronal damage could well be less.

Vinblastine, bleomycin and cisplatin for recurrent or metastatic squamous cell carcinoma of the head and neck

Forty-two patients with recurrent or metastatic squamous cell carcinoma of the head and neck were treated with vinblastine, bleomycin, and cisplatin. All patients had received prior surgery, radiation or chemotherapy and all had measurable disease. Forty-five percent of the patients responded with a median duration of response of eight months and median survival of nine months. Six patients (14%) were complete responders and had a median duration of response of 12 months and median survival of 24+ months. Thirteen patients (31%) were partial responders and had a median duration of response of seven months and survival of 13 months. Toxicity was mild with nausea and vomiting occurring in all patients after cisplatin. There were two cases of bleomycin-induced pulmonary fibrosis and two cases of mild renal insufficiency (creatinine clearance level, 45 cc/min). This regimen compares favorably with other published regimens for advanced head and neck cancer.

The origin of lipid phagocytes in the central nervous system: I. The intrinsic microglia

The potential for the transformation of the normal microglial cell to a lipid phagocyte was studied by light and electron microscopy in the brains of rodents and by light microscopy only in primates. All were subjected to some form of hypoxia-ischemia and the microglial response was examined in regions of selective neuronal destruction (SND) so that infarction was deliberately excluded. In vivo perfusion-fixation was employed in all animals and light microscopic examination was carried out on paraffin- and sometimes celloidin-embedded material. Semithin plastic sections from several regions of the rodent brains were used for light microscopy but ultrastructural studies were confined to the hippocampus. In all animals the microglia were activated and transformed into rod cells exhibiting phagocytic properties but only a minority gave rise to lipid phagocytes. Blood vessels were normal in all animals and no hematogenous elements were identifed in the the parenchyma. As neuronal ghosts could be identified for up to 3 weeks it was concluded that the capacity of the microglia for phagocytic activity was limited.

The origin of lipid phagocytes in the central nervous system: II. The adventitia of blood vessels

The source of the lipid phagocytes that occupy a cerebral infarct has been determined by light and electron microscopy in the brains of rodents and by light microscopy only in the brains of primates. The infarcts (in neocortex, hippocampus, and thalamus) were the consequence of hypoxia-ischemia of various types. Hemorrhagic infarcts were excluded. After in vivo perfusion-fixation, paraffin- and celloidin-embedded material was used for light microscopy. Semithin plastic sections from the neocortex and thalamus were studied with the light microscope and ultrastructural studies were confined to the same regions. In all animals after about 2 days there was evidence of phagocytic activity in the fibroblasts in the adventitia of the remaining large vessels and also proliferation by mitotic division. At 5-7 days fibroblasts appeared to migrate from the vessels in a semifluid or fluid milieu and to give rise to typical phagocytes. These increased in size and number but signs of degeneration became apparent after 10 days and they had largely disappeared by 32 days. Smooth muscle cells and pericytes showed evidence of degeneration and phagocytic activity was never seen in the latter.