Imaging of dopamine transporters and D2 receptors in vascular parkinsonism: a report of four cases

Summary. The role of nuclear medicine imaging in the diagnosis of vascular parkinsonism (VP) has been addressed by only few studies up to now. Most previous reports suggest no or only mild impairment of DAT and D2 receptors in VP. In contrast, in four patients with VP, reported here, the combined DAT and D2 receptor SPECT showed highly unusual changes in the pre- and/or postsynaptic dopaminergic system. The possible value of combined DAT/D2 receptor SPECT imaging should be investigated by future prospective studies. These two authors contributed equally     

99mTc-TRODAT-1 SPECT study in early Parkinson's disease and essential tremor

OBJECTIVE: The clinical differentiation between early Parkinson's disease (PD) and essential tremor (ET) could be difficult, therefore, the aim of this study was to investigate 99mTc-TRODAT-1 SPECT as an applicable tool in this field. METHODS: 99mTc-TRODAT-1 single photon emission computed tomography (SPECT) was performed in 10 healthy volunteers, 27 patients with idiopathic PD (Hoehn and Yahr 1-1.5) and 12 patients with ET. The ratio of striatal (99m)Tc-TRODAT-1 binding was calculated as the index of (striatum - occipital cortex)/occipital cortex. RESULTS: Compared with the striatal 99mTc-TRODAT-1 uptake in the ET group (0.49 +/- 0.07) or healthy controls (0.54 +/- 0.18), there was a significant decrease in the bilateral striatums of early PD, with a greater reduction in the contralateral striatum (0.27 +/- 0.08) than ipsilateral one (0.36 +/- 0.10, P < 0.01). Its sensitivity and specificity of differentiating early PD from ET was 96.4% and 91.7% respectively. CONCLUSION: 99mTc-TRODAT-1 SPECT can detect the dysfunction of nigrostriatal system in patients with early PD and provided a feasible tool to help differentiate early PD from ET.     

Patterns of axonal branching of neurons of the substantia nigra pars reticulata and pars lateralis in the rat

Axons from neurons of the rat substantia nigra pars reticulata (SNr) and pars lateralis (SNl) were traced after injecting their cell body with biotinylated dextran amine. Thirty-two single axons were reconstructed from serial sagittal sections with a camera lucida, whereas four other SNr axons were reconstructed in the coronal plane to determine whether they innervate the contralateral hemisphere. Four distinct types of SNr projection neurons were identified based on their main axonal targets: type I neurons that project to the thalamus; type II neurons that target the thalamus, the superior colliculus (SC), and the pedunculopontine tegmental nucleus (PPTg); type III neurons that project to the periaqueductal gray matter and the thalamus; and type IV neurons that target the deep mesencephalic nucleus (DpMe) and the SC. The axons of the SNl showed the same branching patterns as SNr axons of types I, II, and IV. The coronal reconstructions demonstrated that SNr neurons innervate the thalamus, the SC, and the DpMe bilaterally. At the thalamic level, SNr and SNl axons targeted preferentially the ventral medial, ventral lateral, paracentral, parafascicular, and mediodorsal nuclei. Axons reaching the SC arborized selectively within the deep layers of this structure. Our results reveal that the SNr and SNl harbor several subtypes of projection neurons endowed with a highly patterned set of axon collaterals. This organization allows single neurons of these output structures of the basal ganglia to exert a multifaceted influence on a wide variety of diencephalic and midbrain structures.     

Excitatory synaptic potentials in spastic human motoneurons have a short rise-time

This study assessed whether changes in size or time-course of excitatory postsynaptic potentials (EPSPs) in motoneurons innervating spastic muscle could induce a greater synaptic response, and thereby contribute to reflex hyperexcitability. We compared motor unit (MU) firing patterns elicited by tendon taps applied to both spastic and contralateral (nonspastic) biceps brachii muscle in hemiparetic stroke subjects. Based on recordings of 115 MUs, significantly shortened EPSP rise times were present on the spastic side, but with no significant differences in estimated EPSP amplitude. These changes may contribute to hyperexcitable reflex responses at short latency, but the EPSP amplitude changes appear insufficient to account for global differences in reflex excitability.     

Sural/radial nerve amplitude ratio: reference values in healthy subjects

The sural/radial nerve amplitude ratio (SRAR) has been proposed as a sensitive indicator of early-stage axonal polyneuropathy. However, previous studies did not take into account the effect of sex differences or different calculating methods. To obtain reference values and information on the variability of the SRAR in daily practice, we measured amplitudes of sural and superficial radial sensory nerve action potentials in 106 healthy adults, correlated them with epidemiological variables, and calculated the SRAR in several ways. Our results show that the SRAR is a robust measure, independent of age, weight, sex, or method of calculation. The use of bilateral measurements is recommended. The cut-off value (5th percentile) of 0.2 in these healthy subjects is much lower than found previously, especially compared to defining cut-off values by comparing patients with matched controls. Further study is needed to establish the clinical value of this SRAR in the early detection of axonal polyneuropathies.     

Three-dimensional registration of myocardial perfusion SPECT and CT coronary angiography

OBJECTIVE: In this study, we describe a new technique for three-dimensional registration of CT coronary angiography (CTCA) and gated myocardial perfusion SPECT. METHODS: Twelve patients with known or suspected CAD who underwent CTCA and gated SPECT were enrolled retrospectively. Coronary arteries and their branches were traced using CTCA data manually and reconstructed in three-dimensions. Gated SPECT data were registered and mapped to a left ventricle binary model extracted from CTCA data using manual, rigid and nonrigid registration methods. RESULTS: Three-dimensional reconstruction and volume visualization of both modalities were successfully achieved for all patients. All 3 registration methods gave better quality based on visual inspection, and nonrigid registration gave significantly better results than the other registration methods (p < 0.05). The cost function for three-dimensional registration using nonrigid registration (235.3 +/- 13.9) was significantly better than those of manual and rigid registration (218.5 +/- 15.3 and 223.7 +/- 17.0, respectively). Inter-observer reproducibility error was within acceptable limits for all methods, and there were no significant difference among the methods. CONCLUSION: This technique of image registration may assist the integration of information from gated SPECT and CTCA, and may have clinical application for the diagnosis of ischemic heart disease.     

Increased accumulations of AMsopropyl-p-[123I]-iodoamphetamine related to tumefactive multiple sclerosis

We present a 21-year-old woman with tumefactive multiple sclerosis (MS) that exhibited a rapidly progressive course. There were multiple tumor-mimicking contrast-enhance lesions with surrounding edema and mass effect on magnetic resonance imaging. Both early and delayed brain single photon emission computed tomography (SPECT) with N-isopropyl-p-[123I]-iodoamphetamine demonstrated increased accumulations of the tracer and a high retention on the lesions. The SPECT findings represent a diagnostic pitfall for distinguishing MS from malignant brain tumors in patients with intracranial tumor-like lesions.     

In Vitro Genotoxic and Cytotoxic Effects of Protein Somatic Products from Helminths on Donor Blood Lymphocytes

Protein somatic products of adult helminths Hymenolepis nana and Toxocara canis and secretory-excretory somatic product of Trichinella spiralis larvae in vitro produced genotoxic and cytotoxic effects on donor blood lymphocytes, which manifested in accumulation of single-chain breaks, alkaline-labile sites in nuclear DNA, and apoptotic cells. This effect depended on the concentration of parasitic protein products during coculturing.     

Prospective study of glove perforation in obstetrical and gynecological operations: are we safe enough?

OBJECTIVES: To assess the glove perforation rate, efficacy of double gloving, effect of duration of surgery, expertise of surgeon and operative urgency on the glove perforation rate in obstetrical and gynecologic operations. METHODS: From February to September 2002, double glove protocol was made necessary for all major obstetrical and gynecologic procedures. The operating surgeon, first and second assistant were included in the study. Gloves damage was noted (overt by inspection, occult by hydroinsufflation technique). RESULTS: Of the 156 procedures included in study, 32 procedures were performed (all emergency operations) single-gloved because surgeons found double gloving clumsy (56%), made it difficult to tie knots due to lack of dexterity (24%), or were too tight (20%). One thousand one hundred and twenty single gloves were examined after each procedure by hydroinsufflation. The overall perforation rate was 13.6% (single versus double outer gloves, 13.8% versus l3.2%, P > 0.05). Matching perforations were found in six cases (4.6%). Thus, the protection offered by double gloves was 95.4% even if the outer gloves were perforated. Four inner gloves had preexisting perforations. Sixty unused gloves checked similarly revealed a perforation rate of 1.6%. Emergency cases had higher perforation rate compared to elective surgeries (16.6% versus 10.8%, P < 0.00 1). Surgeries lasting for more than 40 min had a higher perforation rate compared to those finished in less than or equal to 40 min (18.6% versus 7.6%, P < 0.001). The middle finger of the left hand was the most commonly involved. The surgeon, first assistant and second assistant were involved in 73.6, 23.3 and 3.2% cases, respectively. CONCLUSION: Double gloving offers considerable protection against exposure to contaminants in the blood and body fluids of the patient and should be made routine, especially in developing countries where HIV, hepatitis B and C are widely prevalent. Double gloving should be made mandatory in emergency procedures, which have a higher perforation rate due to operative urgency, and gloves should be changed in operations lasting for more than 40 min to ensure integrity of barrier.