Torsion of intraperitoneal renal transplants: imaging appearances

OBJECTIVE: Torsion of a renal transplant is a rare complication with nonspecific clinical manifestations. Prompt detection is necessary to allow surgical treatment and to preserve renal function. We describe the radiologic appearances of torsion of intraperitoneal renal transplants in patients who have undergone simultaneous renal and pancreatic transplantation or dual renal transplantation. CONCLUSION: Renal transplant torsion should be suspected when a change in renal axis associated with abnormal perfusion occurs in an intraperitoneal kidney.     

Regulation of the NMDA component of EPSPs by different components of postsynaptic GABAergic inhibition: computer simulation analysis in piriform cortex

Regulation of the NMDA component of EPSPs by different components of postsynaptic GABAergic inhibition: computer simulation analysis in piriform cortex. J. Neurophysiol. 78: 2546-2559, 1997. Physiological analysis in the companion paper demonstrated that gamma-aminobutyric acid-A (GABAA)-mediated inhibition in piriform cortex is generated by circuits that are largely independent in apical dendritic and somatic regions of pyramidal cells and that GABAA-mediated inhibitory postsynaptic currents (IPSCs) in distal dendrites have a slower time course than those in the somatic region. This study used modeling methods to explore these characteristics of GABAA-mediated inhibition with respect to regulation of the N-methyl--aspartate (NMDA) component of excitatory postsynaptic potentials. Such regulation is relevant to understanding NMDA-dependent long-term potentiation (LTP) and the integration of repetitive synaptic inputs that can activate the NMDA component as well as pathological processes that can be activated by overexpression of the NMDA component. A working hypothesis was that the independence and differing properties of IPSCs in apical dendritic and somatic regions provide a means whereby the NMDA component and other dendritic processes can be controlled by way of GABAergic tone without substantially altering system excitability. The analysis was performed on a branched compartmental model of a pyramidal cell in piriform cortex constructed with physiological and anatomic data derived by whole cell patch recording. Simulations with the model revealed that NMDA expression is more effectively blocked by the slow GABAA component than the fast. Because the slow component is present in greater proportion in apical dendritic than somatic regions, this characteristic would increase the capacity of dendritic IPSCs to regulate NMDA-mediated processes. The simulations further revealed that somatic-region GABAergic inhibition can regulate the generation of action potentials with little effect on the NMDA component generated by afferent fibers in apical dendrites. As a result, if expression of the NMDA component or other dendritic processes were enabled by selective block of dendritic inhibition, for example, by centrifugal fiber systems that may regulate learning and memory, the somatic-region IPSC could preserve system stability through feedback regulation of firing without counteracting the effect of the dendritic-region block. Simulations with paired inputs revealed that the dendritic GABAA-mediated IPSC can regulate the extent to which a strong excitatory input facilitates the NMDA component of a concurrent weak input, providing a possible mechanism for control of "associative LTP" that has been demonstrated in this system. Postsynaptic GABAB-mediated inhibition had less effect on the NMDA component than either the fast or slow GABAA components. Depolarization from a concomitant alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) component also was found to have comparatively little effect on current through the NMDA channel because of its brief time course.     

Influence of projected complication rates on estimated appropriate use rates for carotid endarterectomy. Appropriateness Project Investigators. Academic Medical Center Consortium

OBJECTIVE: To examine specifically the influence of estimated perioperative mortality and stroke rate on the assessment of appropriateness of carotid endarterectomy. DATA SOURCES/STUDY SETTING: An expert panel convened to rate the appropriateness of a variety of potential indications for carotid endarterectomy based on various rates of perioperative complications. We then applied these ratings to the charts of 1,160 randomly selected patients who had carotid endarterectomy in one of the 12 participating academic medical centers. STUDY DESIGN: An expert panel evaluated indications for carotid endarterectomy using the modified Delphi approach. Charts of patients who received surgery were abstracted, and clinical indications for the procedure as well as perioperative complications were recorded. To examine the impact of surgical risk assessment on the rates of appropriateness, three different definitions of risk strata for combined perioperative death or stroke were used: Definition A, low risk < 3 percent; Definition B, low risk < 5 percent; and Definition C, low risk < 7 percent. PRINCIPAL FINDINGS: Overall hospital-specific mortality ranged from 0 percent to 4.0 percent and major complications, defined as death, stroke, intracranial hemorrhage, or myocardial infarction, varied from 2.0 percent to 11.1 percent. Most patients (72 percent) had surgery for transient ischemic attack or stroke; 24 percent of patients were asymptomatic. Most patients (82 percent) had surgery on the side of a high-grade stenosis (70-99 percent). When the thresholds for operative risk were placed at the values defined by the expert panel (Definition A), only 33.5 percent of 1,160 procedures were classified as "appropriate." When the definition of low risk was shifted upward, the proportion of cases categorized as appropriate increased to 58 percent and 81.5 percent for Definitions B and C, respectively. CONCLUSIONS: Despite the high proportion of procedures performed for symptomatic patients with a high degree of ipsilateral extracranial carotid artery stenosis and generally low rates of surgical complications at the participating institutions, the overall rate of "appropriateness" using a perioperative complication rate of < 3 percent was low. However, the rate of "appropriateness" was extremely sensitive to judgments about a single clinical feature, surgical risk. These data show that before applying such "appropriateness" ratings, it is crucial to perform sensitivity analyses in order to assess the stability of the results. Results that are robust to moderate in variation in surgical risk provide a much sounder basis for policy making than those that are not.     

Metabolism, intensity of lipid peroxidation and the antioxidant defense system in humans during chamber experiments with long-term isolation

Blood biochemical parameters of lipid, protein, carbohydrate and energy metabolism were measured in a 135-day chamber experiment. Also, dynamics of the intensity of lipid peroxidation and status of the antioxidant defence system were evaluated. Results of the investigation showed that extended chamber isolation led to modifications of several biochemical parameters including hemoglobin, bilirubin, cholesterol and its fractions, elevated transaminase activity which are typical for long-term space mission. However, these were not accompanied by substantive changes in protein, energy and carbohydrate metabolisms, or intensity of free radical processes. Effects of prolonged stay in chamber was successfully counterbalanced by organism.     

Postmortem diagnosis of leukodystrophies

Leukodystrophies are progressive disorders involving the development and maintenance of myelin in the central and peripheral nervous systems. Although relatively uncommon, leukodystrophic disorders may be undiagnosed or misdiagnosed during life, and may appear as "sudden death." In such instances, these victims may be referred to a forensic pathologist. In general, leukodystrophies are inherited in an autosomal recessive manner so that proper postmortem diagnosis by the forensic pathologist is extremely important to the decendant's family for future family planning.     

Origin of HIV-1 in the chimpanzee Pan troglodytes troglodytes

The human AIDS viruses human immunodeficiency virus type 1 (HIV-1) and type 2 (HIV-2) represent cross-species (zoonotic) infections. Although the primate reservoir of HIV-2 has been clearly identified as the sooty mangabey (Cercocebus atys), the origin of HIV-1 remains uncertain. Viruses related to HIV-1 have been isolated from the common chimpanzee (Pan troglodytes), but only three such SIVcpz infections have been documented, one of which involved a virus so divergent that it might represent a different primate lentiviral lineage. In a search for the HIV-1 reservoir, we have now sequenced the genome of a new SIVcpzstrain (SIVcpzUS) and have determined, by mitochondrial DNA analysis, the subspecies identity of all known SIVcpz-infected chimpanzees. We find that two chimpanzee subspecies in Africa, the central P. t. troglodytes and the eastern P. t. schweinfurthii, harbour SIVcpz and that their respective viruses form two highly divergent (but subspecies-specific) phylogenetic lineages. All HIV-1 strains known to infect man, including HIV-1 groups M, N and O, are closely related to just one of these SIVcpz lineages, that found in P. t. troglodytes. Moreover, we find that HIV-1 group N is a mosaic of SIVcpzUS- and HIV-1-related sequences, indicating an ancestral recombination event in a chimpanzee host. These results, together with the observation that the natural range of P. t. troglodytes coincides uniquely with areas of HIV-1 group M, N and O endemicity, indicate that P. t. troglodytes is the primary reservoir for HIV-1 and has been the source of at least three independent introductions of SIVcpz into the human population.     

Dynamics of tremor-related oscillations in the human globus pallidus: a single case study

Physiological evidence indicates that the resting tremor of Parkinson's disease originates in oscillatory neural activity in the forebrain, but it is unknown whether that activity is globally synchronized or consists of parallel, independently oscillating circuits. In the present study, we used dual microelectrodes to record tremor-related neuronal activity from eight sites in the internal segment of the globus pallidus (GPi) from an awake Parkinson's disease patient undergoing stereotaxic pallidotomy. We utilized spectral analysis to evaluate the temporal correlations between multiunit activity at spatially separated sites and between neural and limb electromyographic activity. We observed that some GPi neural pairs oscillated synchronously at the tremor frequency, whereas other neural pairs oscillated independently. Additionally, we found that GPi tremor-related activity at a given site could fluctuate between states of synchronization and independence with respect to upper limb tremor. Consistent with this finding, some paired recording sites within GPi showed periods of transient synchronization. These observations support the hypothesis of independent tremor-generating circuits whose coupling can fluctuate over time.     

Relation between maternal diet and subsequent primitive neuroectodermal brain tumors in young children

BACKGROUND: It has been hypothesized that a high dietary intake of nitrosamines and their precursors, nitrites and nitrates, is a risk factor for brain tumors. Vitamins C and E inhibit the formation of nitrosamines and thus may be protective. METHODS: We conducted a case-control study of maternal diet and the risk of primitive neuroectodermal tumors of the brain in children. The case patients were under the age of six years at diagnosis in 1986 to 1989. The controls were selected by random-digit telephone dialing and were matched for age and race to 166 case patients. Telephone interviews with the mothers included questions on the frequency of consumption of alcohol, vitamin and mineral supplements, and 53 foods during pregnancy. RESULTS: Significant protective trends were observed for vegetables (odds ratio for the highest quartile group for intake relative to the lowest, 0.37; P for trend = 0.005), fruits and fruit juices (odds ratio, 0.28; P = 0.003), vitamin A (odds ratio, 0.59; P = 0.03), vitamin C (odds ratio, 0.42; P = 0.009), nitrate (odds ratio, 0.44; P = 0.002), and folate (odds ratio, 0.38; P = 0.005). A nonsignificant trend of increasing risk was observed for nitrosamine (odds ratio, 1.65; P = 0.15). The use of iron (odds ratio, 0.43; P = 0.004), calcium (odds ratio, 0.42; P = 0.05), and vitamin C (odds ratio, 0.35; P = 0.04) supplements at any time during the pregnancy and the use of multivitamins during the first six weeks (odds ratio, 0.56; P = 0.02) were associated with decreased risk. In multivariate analyses, folate, early multivitamin use, and iron supplements generally remained protective. CONCLUSIONS: These results do not support the hypothesis that nitrosamines have a role in the development of primitive neuroectodermal tumors in young children, but they do suggest that certain other aspects of maternal diet can influence the risk.     

Cutanea tarda porphyria in 2 patients with kidney transplantation

In rheumatoid synovium interleukin 6 (IL-6) is the most abundantly expressed cytokine. Increased serum levels have been previously reported in patients with rheumatoid arthritis (RA). In this study serum IL-6 levels were measured in a well defined cohort using a bioassay (B9 cells) and levels were correlated with conventional clinical and laboratory indices of disease activity. Levels were significantly higher in serum from patients with RA (median 55 IU/ml; interquartile range 28-139) compared with serum from disease (median 7 IU/ml; 1-23) and normal controls (median 10 IU/ml; 7-12). No difference was observed between men and women. Levels did not correlate with disease duration. Significant associations were observed between IL-6 and C reactive protein and between the Ritchie articular index and duration of morning stiffness. No other correlations were observed. The value of these findings in the monitoring of RA and as an indicator of response to second line treatment needs to be established.