Selective ablation of porcine and rabbit liver tissue using radiofrequency: preclinical study

Temperature changes and their distribution induced by 13.56-MHz radiofrequency (RF) heating of agar phantom and porcine and rabbit liver were investigated. It was possible to produce selective local heating of approximately 50 degrees C in the RF field of 2 x 2 x 2 cm(3) of the pig or rabbit liver. Coagulation necrosis after heating became pronounced and the margin between the coagulated lesion and normal tissue became clearer with time. Within 1 week after RF heating at 50 degrees C for 20 min, the coagulated area was replaced selectively and totally by necrotic tissue.     

Bone Metastases from Soft Tissue Sarcomas

The incidence, distribution, time of appearance, and radiologic findings of bone metastases from soft tissue sarcomas, exclusive of lymphomas, were evaluated in 320 patients with soft tissue sarcomas. Thirty patients (9.4%) had evidence of 58 bone metastases. Five of 30 patients presented with metastases, and 25 of 30 patients developed metastases up to 66 months after presentation with a mean time interval of 21.3 months. The incidence of skeletal metastases differed among histologic subtypes of sarcomas; alveolar soft part sarcoma (5 of 8), dedifferentiated liposarcoma (2 of 4), angiosarcoma (2 of 4), and rhabdomyosarcoma (5 of 16) tended to show a higher incidence of bone metastases. The sarcomas metastasized to the regional bones close to the primary tumor in 16 (53%) of 30 patients and to the axial bones in 18 (60%). On conventional radiographs, the osseous metastases demonstrated predominantly osteolytic changes, and evidence of pathological fracture was observed in 31% of 58 metastases.     

Trans-synaptically induced bursts in regular spiking non-pyramidal cells in deep layers of the cat motor cortex

In deep layers of the cat motor cortex, we have investigated the properties of neurons displaying trans-synaptically induced bursts. In in vivo experiments, extracellularly recorded burst neurons were separated into two subtypes based on their dependence on stimulation sites, the medullary pyramid or the ventrolateral (VL) thalamic nucleus, from which bursts of 10-20 spikes were triggered. The spike amplitude attenuation and frequency adaptation during a burst were more prominent in pyramid-dependent burst neurons than in VL-dependent burst neurons. Intracellular recordings in in vivo experiments revealed that pyramid-dependent bursts emerged from a long-lasting depolarization, while each spike during a VL-dependent burst was narrow in half-width and was followed by a fast AHP, similar to fast spiking neurons. In in vitro slice experiments, intracellular recordings were obtained from neurons that displayed a burst of attenuated spikes emerging from a long-lasting depolarization, and were also obtained from fast spiking neurons. They were morphologically recovered to be multipolar cells with sparsely spiny dendrites and local axonal networks, suggesting that they are inhibitory interneurons. The multipolar neurons displaying bursts of attenuated spikes may mediate the recurrent inhibition of pyramidal tract cells.     

Multiple chemical sensitivities: case definition, etiology and relations to allergy, poisoning, psychogenic illness etc]

Multiple Chemical Sensitivities (MCS) have been defined as an acquired disorder characterized by recurrent symptoms, referable to multiple organ systems, occurring in response to demonstrable exposure to many chemically unrelated compounds at doses far below those established in the general population to cause harmful effects; no single widely accepted test of physiologic function can be shown to correlate with symptoms (Cullen MR, 1987). The etiology of MCS is hypothesized as a toxicant-induced loss of tolerance to multiple chemicals with subsequent manifestation of multiple-organ symptoms triggered by low-level exposure to such chemicals. The involvement of multiple organs might be attributed to a neurogenic switching mechanism. The final diagnosis of MCS is to rely on provocation of symptoms in a exposure chamber by a double-blind method. Relations of MCS to allergy, poisoning, psychogenic illness, chemical sensitivity, idiopathic environmental intolerances etc. are discussed in terms of case definition and etiology of these disorders.     

Recovery of slowed nerve conduction velocity in lead-exposed workers

Summary Maximum motor nerve conduction velocities in the median nerve (MCV) and blood lead (PbB) were repeatedly measured in 14 lead exposed workers with an initial PbB from 0.7 to 4.0 mol/kg (median 2.3 mol/kg) for a period from 3 months to 7 years: A certain dose of Calcium Disodium Ethylenediaminetetraacetic Acid (CaEDTA) was injected intravenously into most of the subjects during the period.In seven subjects, MCV improved by more than 4 m/s during the observation period which involved the first two successive measurements of MCV and PbB, but the remaining seven subjects showed the minimal alteration (within ± 4.0 m/s). The initial value of MCV was significantly slower (P < 0.01) and the decrease in PbB was significantly greater (P < 0.05) in the group of subjects having shown the improvement of MCV by more than 4 m/s.The initial value of MCV was significant in determining the alteration in MCV in multiple regression analysis and, together with the change in PbB, explained 31% of the alteration in MCV between the first two successive measurements. The initial level of PbB, dose of CaEDTA, time interval between the measurements and age played no essential part in the alteration in MCV.The alteration in MCV throughout the whole observation period in each subject significantly correlated with the concurrent change in PbB (r=–0.573, P < 0.001).     

Arterial occlusion following cerebral vasospasm (author's transl)]

1. The present study analysed the clinical course, the serial angiograms and the CT scans of the patients with angiographic arterial occlusion following vasospasm after subarachnoid hemorrhage. The occlusion was observed in 6 out of 84 patients with vasospasm. 2. The angiograms which showed this phenomenon were obtained between the 11th and the 30th day of the illness. The affected vessels were the branches of middle cerebral artery. 3. Thrombus formed on the intima which had been injured by vasospasm is suspected to be a genesis of this arterial occlusion. The pathological findings of a case in this series support this concept. 4. The surgical procedure during the direct aneurysmal operation performed in the period of "smooth narrowing" seems to be a contributing factor to the arterial occlusion. There was no correlation between antifibrinolytic therapy and this phenomenon except in one case. 5. Fibrinolytic therapy after clipping of aneurysm may be a treatment of choice for this arterial occlusion following vasospasm.     

Endoscopic surgery in obstetrics and gynecology

There are three types of endoscopic surgery in obstetrics and gynecology: laparoscopy; hysteroscopy; and salpingoscopy. The main indications for laparoscopic surgery are myoma uteri, ovarian tumors, ectopic pregnancy, infertility, and endometriosis. Currently the indications are limited to benign disease. The main indications for hysteroscopic surgery are submucous myoma uteri, uterine anormalies, and Asherman syndrome. During hysteroscopy the uterine cavity is dilated with liquid and then a resectoscope or hysterofiberscope is used. Salpingoscopy is useful in examining the tubal cavity and a potent tool for tubal recanalization. Endoscopic surgical techniques will develop rapidly in the near future to serve the various needs of female patients.     

Mechanisms for the formation of glycoxidation products in end-stage renal disease

BACKGROUND: Advanced glycation end products (AGEs) accumulate on tissue and plasma proteins in patients with renal failure far in excess of normal aging or diabetes. The aim of these studies was to elucidate the nature of the precursors and the pathways that lead to an accelerated formation of two structurally identified AGEs [pentosidine and Nepsilon(carboxymethyl)lysine (CML)] in the uremic milieu. METHODS: Serum levels of the glycoxidation products, pentosidine and CML, were quantitated by high-performance liquid chromatography in uremic patients treated by dialysis. The formation of early glycation products (as furosine) and late glycoxidation products was modeled in uremic serum and in spent peritoneal dialysate. RESULTS: Clinical factors that affect circulating levels of AGEs included dialysis clearance and dialyzer membrane pore size, but not the presence or absence of diabetes. Both pentosidine and CML form at an accelerated rate in serum from uremic patients. Chelating agents most effectively slow the formation in vitro. In uremic fluids, the primary mechanism of formation of pentosidine is through the Amadori pathway. The primary mechanism of formation of CML is through metal-chelated autoxidation of reducing sugars generating reactive carbonyl precursors. In uremic serum, the presence of an unidentified reactive low molecular weight precursor accelerates the formation of pentosidine. CONCLUSIONS: The formation of the two glycoxidation products, pentosidine and CML, proceeds by different pathways and is enhanced by different precursors in the uremic milieu. The formation of both AGEs is markedly enhanced by metal-catalyzed reactions, evidence for the presence of increased metal-ion mediated oxidant stress in uremia.     

Decrease of glucose utilization rate in the spinal cord of experimental 2,5-hexanedione poisoning rats: application of microdetermination technique

To examine the effects of 2,5-hexanedione (HD) on the glucose metabolism in the spinal cord, glucose utilization rate (GUR) and distribution volume of glucose (DV) were measured in the white matter and anterior horn of the spinal cord in 8 rats exposed to HD for 4 weeks and in 10 control rats. The GUR and DV were determined by the quantitative microdetermination method using non-tracer 2-deoxyglucose based on the three-compartments model of Sokoloff. GURs in the white matter and anterior horn and DV in the anterior horn in the HD-exposed rats were significantly lower than those in the control rats. In the multiple regression analysis, GUR in the white matter of HD-exposed rats was significantly related to blood HD concentration. It is suggested that the decrease of GUR in the white matter is a major effect of HD in the spinal cord.