Effects of aerial spraying of insecticides on nontarget macrobenthos in a mountain stream

The effects of aerial spraying of an insecticide were investigated in a mountain stream using a drift net. The concentration of fenitrothion (organophosphorus insecticide) in the river water increased to ca. 20 micrograms liter-1 3 hr after the spraying and decreased exponentially to half the peak value after 2 hr. A large number of aquatic insects were found drifting after the spraying. The total number of individuals which drifted in the daytime after spraying reached nine times the number found the previous night. The total number of species which drifted during the 24 hr following the spray increased to 43 from 17 on the previous day. Before the insecticide spraying, the drifting benthos were almost entirely made up of three species of Baetis (Ephemeroptera). However, many individuals of several species of Heptageniidae (Ephemeroptera), Apsilochorema sutshanum (Trichoptera), and Chironomidae (Diptera) drifted in addition to Baetis after the spray. A large number of young Baetis, which had not been seen in the natural night drift samples, were found drifting due to the insecticide. Natural night drift almost disappeared from the day following insecticide spraying. At the second insecticide spraying, conducted 20 days after the first, the number of individuals which drifted during the 24 hr following spraying decreased to only 0.85% of that in the first spraying although changes in insecticide concentration showed a similar pattern. Several species of Ephemeroptera were dominant among the fauna in the studied stream, and the causal relationships of this are discussed.     

Organized thrombus of the tricuspid valve mimicking valvular tumor

We report on a case of organized thrombus of the tricuspid valve mimicking a valve tumor. Preoperative transesophageal echocardiography showed the mass to have originated from the septal leaflet of the tricuspid valve. A pouch of the tricuspid valve and a ventricular septal defect were observed perioperatively, with the mass attached to the septal leaflet. Histologic examination revealed the mass to be an organized thrombus without tumor components.     

Intrahepatic recurrences of hepatocellular carcinoma after hepatectomy: analysis based on tumor hemodynamics.

HYPOTHESIS: Surgical margin, i.e., the area of possible local intrahepatic metastasis, is controversial in hepatectomy for hepatocellular carcinoma. DESIGN: The blood drainage area of tumor was identified preoperatively by abdominal helical computed tomographic scan under hepatic arteriography and excised as surgical margin. The specimens were pathologically examined on the basis of the corresponding computed tomographic images. SETTING: University hospital. PATIENTS: From June 2, 1997, to April 24, 2000, 67 patients with hepatocellular carcinoma who underwent curative hepatic resection. MAIN OUTCOME MEASURE: Intrahepatic recurrence. RESULTS: Blood drainage area of tumor could be classified into the following types. The marginal type (drainage into the peritumorous area) was frequent (50 cases) and excised mostly by nonanatomic, limited resection. Portal vein type (drainage into the portal branches) was less common (12 cases) and resected mostly by anatomically systematic hepatectomy. The remaining 5 cases were of the hypovascular type and underwent limited resection. Multiple nodules were frequently found inside the drainage area (4 of 8 cases) and were moderate or poorly differentiated hepatocellular carcinoma, consistent with intrahepatic metastasis. Solitary nodules were mostly outside the drainage area (11 of 12 cases) and contained well-differentiated hepatocellular carcinoma (7 of 10 cases), suggesting multicentric carcinogenesis. Intrahepatic recurrences were commonly found in bilateral or contralateral lobes (17 of 19 cases) and divided into 2 groups with a few (< or =4) and multiple (> or =8) recurrent nodules. CONCLUSIONS: Surgical margin varied according to tumor hemodynamics. Tumor recurrences may result not only from multicentric carcinogenesis but also from intrahepatic metastasis via systemic circulation.     

Comparison of protein phosphatase inhibitory activity and apparent toxicity of microcystins and related compounds.

Two metabolites of microcystin-LR glutathione conjugate and, microcystin-cysteine conjugate, as well as microcystin-RR (MCRR) are less toxic than microcystin-LR (MCLR). In the present study, we investigated why these compounds are weakly toxic in comparison with MCLR, as the reason is still unknown and no systematic study has so far been carried out for a clarification of this issue. Although they showed almost the same inhibitory activity against protein phosphatases 1 and 2A as MCLR in vitro, the apparent toxicity of these three compounds by intratracheal administration to mice decreased to about 1/12 the level of MCLR at 100microg/kg. An immunostaining study showed that these conjugates at a sublethal dose of 200microg/kg were prominently observed in the intestine and kidney, whereas effective accumulation and bleeding were not found in the liver in spite of the larger dosage. As an explanation for these results, there may be two possibilities. First, the transport system to the liver might not function well, and second, transported toxins may be effectively eliminated by an appropriate system such as the GS-X (ATP-dependent glutathione S-conjugate exported) pump. It was concluded that the inhibitory activity against protein phosphatases is not always related to the apparent LD(50) level, and that the appearance of toxicity by microcystins depends on the balance between accumulation and metabolism in the liver.     

Environmental enrichment stimulates progenitor cell proliferation in the amygdala

Enriched environments enhance hippocampal neurogenesis, synaptic efficacy, and learning and memory functions. Recent studies have demonstrated that enriched environments can restore learning behavior and long‐term memory after significant brain atrophy and neural loss. Emotional and anxiety‐related behaviors were also improved by enriched stimuli, but the effect of enriched environments on the amygdala, one of the major emotion‐related structures in the central nervous system, remains largely unknown. In this study, we have focused on the effects of an enriched environment on cell proliferation and differentiation in the murine amygdala. The enriched environment increased bromodeoxyuridine (BrdU)‐positive (newborn) cell numbers in the amygdala, almost all of which, immediately after a 1‐week period of enrichment, expressed the oligodendrocyte progenitor marker Olig2. Furthermore, enriched stimuli significantly suppressed cell death in the amygdala. Some of the BrdU‐positive cells in mice exposed to the enriched environment, but none in animals housed in the standard environment, later differentiated into astrocytes. Our findings, taken together with previous behavioral studies, suggest that progenitor proliferation and differentiation in the amygdala may contribute to the beneficial aspects of environmental enrichment such as anxiolytic effects. © 2009 Wiley‐Liss, Inc.     

Partial Characterization of Mechanisms of Cytoprotective Action of Hydrophilic Bile Salts Against Hydrophobic Bile Salts in Rats (Relation to Canalicular Membrane Fluidity and Packing Density)

Bile salts regulate the subselection ofphosphatidylcholine species secreted into bile andthereby modulate bile metastability. The aim of thisstudy was to determine whether bile salts alterphosphatidylcholine species of the canalicular membrane, and ifthey do, to clarify whether the cytoprotective action ofhydrophilic bile salts is associated with modulation ofphosphatidylcholine composition in cell membrane bilayers. Bile salt-pool-depleted rats wereinfused intravenously with sodium taurocholate at aconstant rate (200 nmol/min/100 g body wt) for 2 hr,followed by infusion of either sodiumtauroursodeoxycholate, sodium tauroalphamuricholate, or sodiumtaurobetamuricholate (200 nmol/min/100 g) for 2 hr.Biliary outputs of cholesterol and phosphatidylcholineand phosphatidylcholine hydrophobicity in bile andsubcellular fractions were determined. The cytoprotectiveaction of hydrophilic bile salts was determined by therelease of canalicular membrane-localizing enzymes(alkaline phosphatase, leucine aminopeptidase) into bile. Tauroursodeoxycholate,taurobetamuricholate, and tauroalphamuricholatedecreased the release of these enzymes when compared tovalues under taurocholate infusion. Bilephosphatidylcholine hydrophobicity was also decreased by the bile salts, whereasthe cholesterol/phosphatidylcholine ratio was increased.In contrast, phosphatidylcholine hydrophobicity in thecanalicular membrane was increased by these three bile salts. In conclusion, hydrophilicbile salts promote biliary secretion of relativelyhydrophilic phosphatidylcholine secretion into bile, andconsequently phosphatidylcholine hydrophobicity in canalicular membranes increased. Such analteration in phosphatidylcholine species withincanalicular membrane enhances its lateral packingdensity with less fluidity, and this may account, inpart, for the cytoprotective action of hydrophilic bilesalts against hydrophobic bile salts.     

Chronic dizziness in elderly people: its clinical characteristics and magneto-encephalographic findings]

Many elderly people complain dizziness which may continue occasionally for months or years. According to epidemiological studies, 25-29% of subjects with more than 60 years of age have the experience of dizziness. Dizziness occurs most commonly during head positional changes or walking. Clinical studies have indicated that causes of dizziness are nonspecific and multi-factorial; cerebrovascular diseases, cervical spondylosis, depressive state, poor vision, orthostatic hypotension, whiplash injury, or low cerebrospinal fluid syndrome may play a role in the development of dizziness. Patients with dizziness commonly have neck/shoulder pain, insomnia, left-right imbalance of visual acuity, scoliosis, white matter lesions on head MRI. Little, however, has yet been known as to how these symptoms and radiological findings are related to mechanisms of dizziness. During the last several years, we performed cerebral functional studies using auditory-evoked magneto-encephalography (MEG) in elderly people with chronic dizziness. Two types of functional abnormalities were found in dizziness patients. One is a rotational abnormality of MEG signals at the temporal cortex (Type A) which can be detected by current arrow mapping analysis. This abnormality is similar to that detected by non-evoked MEG in temporal lobe epilepsy patients. In patients with Type A abnormality, administration of anticonvulsants brought about dramatic improvement of dizziness in association with disappearance of rotational abnormalities. The other is abnormal prolongation of interhemispheric neural conduction time (INCT) between the left and right temporal cortices (Type B) which can be estimated from the difference of left and right N100 m peak latencies. The INCT was found to be prolonged correlating with the grade of white matter lesions on MRI. The INCT also seems to be prolonged by lack of sleep. Patients with Type B abnormality commonly have the asymmetry of body, such as left-right imbalance of visual acuity, left-right neck pain, or remarkable scoliosis, in association with insomnia and/or depressive state. According to the study of Penfield, dizziness or vertigo is manifested by stimulation of upper temporal cortex and lower parietal cortex. Mechanisms of dizziness can be hypothecated on the basis of MEG findings as follows: Presumably, there are head-position recognizing (HPR) centers in the left and right cerebral hemispheres. The HPR centers may correspond to the vestibular cortex or the combined system of vestibular, visual and somatosensory cortices. The HPR centers in two hemispheres are receiving head-position signals from vestibular, visual and somatosensory corices and are readjusting the dissociation of information which may exist between each other through rapid interhemispheric neural conduction. In patients with Type A abnormality, dizziness may be caused by abnormal neuronal excitements in left or right HPR center. In patients with Type B abnormalities, dizziness may be caused by the combined factors, one the abnormal prolongation of INCT between left and right HPR centers and the other the large dissociation of head position signals between the left and right HPR centers due to the body asymmetry, such as scoliosis or left-right neck pain imbalance.     

The efficacy of the fluorescent conjugates of cholera toxin subunit B for multiple retrograde tract tracing in the central nervous system

Cholera toxin subunit B (CTB) is a sensitive neuroanatomical tracer that generally transports retrogradely in the nervous system, and has been used extensively in brightfield microscopy. Recently, Alexa Fluor (AF) conjugates of CTB have been made available, which now allows multiple tracing with CTB. In this study, we examined the efficacy of these new AF-CTB conjugates when injected into the brain, and compared the results to our previous experiences using fluorescent 3k dextran amines. To test this, we injected AF 488 and AF 594 CTB into the anterior cingulate cortex and the medial agranular cortex in the rat, and examined the retrograde transport to the lateral posterior nucleus of the thalamus. We found that CTB was very viscous but yet very sensitive: small injection sites revealed very intense and detailed retrograde labeling. Anterograde transport was seen only when tissue at the injection site was damaged. These findings suggest that AF-CTB is a very reliable and sensitive retrograde tracer, and should be the first choice retrograde tracer for experiments examining multiple pathways within the same brain.     

Pharmacokinetics of calcitriol and maxacalcitol administered into peritoneal dialysate bags in peritoneal dialysis patients.

OBJECTIVES: It is well known that injection of calcitriol (CT) or maxacalcitol (OCT) is very effective in hemodialysis patients with secondary hyperparathyroidism (2HPT). However, it is difficult to use these drugs with peritoneal dialysis (PD) patients with 2HPT because these drugs must be injected two or three times per week. The objective of the present study was to evaluate the stability of physiological activities of CT and OCT in PD bags and to determine the CT or OCT dosage for intraperitoneal (IP) administration. MATERIALS AND METHODS: We added CT 1.5 microg or OCT 10 microg to Dianeal PD-2 (approximate pH = 5.0, calcium = 0.87 mmol/L; Baxter,Tokyo, Japan), Midpeliq 250 (approximate pH = 7.0, Ca = 1.0 mmol/L;Terumo Corporation, Tokyo, Japan), and Peritoliq 250 (approximate pH = 5.5, Ca = 1.0 mmol/L; Terumo Corp.). Dialysis solutions were collected from the PD bags at 0, 1, 4, 8, 12, 24, 48, and 72 hours after addition of CT and OCT. The activities of CT and OCT in the dialysis effluent were measured by radioimmunoassay. The levels of serum and effluent OCT after a single IP administration of 10 microg OCT were examined in 4 PO patients with advanced 2HPT. RESULTS: Although the levels of CT and OCT in PD bags made of polyvinyl resins decreased by 70% - 75% immediately after injection, levels in PD bags made of polypropylene resins decreased only slightly. The concentration of CT mixed into the acidic solution in glass containers was stable; the decreased concentration of CT in the PD solution might be due to adsorption onto polyvinyl resins. The maximum serum concentration after IP administration of 10 microg OCT was 750 pg/mL after 5 minutes, and remained at 500 pg/mL at 60 minutes. These results show good peritoneal transport of OCT but not rapid disappearance, unlike intravenous administration. CONCLUSIONS: If peritoneal administration of vitamin D derivatives is contemplated, it is important to select the composition of PD bag resins, type of vitamin D analog, and time lag to use when deciding the dosage of injectable vitamin D preparations, such as OCT or CT, for IP administration to PD patients. It appears that IP administration in overnight dwells might be useful for PD patients as a complementary vitamin D preparation.