Criteria for the Formation of Sediment Plugs in Alluvial Rivers

A sediment plug is defined as aggradation in a river that completely blocks the main channel. Information from documented cases of sediment plug development in alluvial rivers was used to develop criteria for plug formation and to identify the setup conditions for sites that are prone to plug formation. Site characteristics, processes, and associated parameters were evaluated based on a comprehensive literature review and evaluation of data. A plug formation theory was developed and tested using a unique sediment transport/movable bed numerical model that simulates the key processes considered to affect plug formation. The theory and model were calibrated and validated against field data, and then used to develop simplified criteria that can be used to predict plug formation. Findings from this study can be used to identify sites that may be prone to plug formation, and the criteria can be used to evaluate the potential for plug formation based upon field site conditions when data are not available to complete a more detailed study.     

Chemical Dynamics and Critical Phenomena: Electrical Conductivity and Reactivity of Benzyl Bromide in Triethylamine+Water Near its Consolute Point

The binary liquid mixture of triethylamine+water has a lower consolute point at a critical composition of 32.27mass% triethylamine. Starting at a temperature within the one-phase region, the electrical conductivity of a sample of this mixture was measured and found to increase smoothly with increasing temperature before falling sharply at 291.24K (18.09°C). Since opalescence was visible at this temperature, it was identified with the critical solution temperature of the binary mixture. A solution of 90μL of benzyl bromide dissolved in 90mL of 32.27mass% triethylamine+water was prepared, and the resulting Menschutkin reaction between benzyl bromide and triethylamine was allowed to come to equilibrium. The electrical conductivity of this equilibrium mixture was measured in the one-phase region and was found to increase smoothly with increasing temperature before rising sharply at 291.55K (18.40°C). This temperature was identified as the critical temperature of the ternary. The rate of approach of the ternary mixture to chemical equilibrium was also measured and shown to be governed by a first-order rate law. The temperature dependence of the rate coefficient followed the Arrhenius equation up to a temperature of about 290.74K (17.59°C). Above this temperature, the rate coefficient fell by as much as 22% below the value predicted by extrapolation of the Arrhenius equation. This suppression in the rate reaction in the vicinity of the critical temperature can be interpreted as evidence for the existence of critical slowing down.     

Concomitant infection with tick-borne encephalitis virus and Borrelia burgdorferi sensu lato in patients with acute meningitis or meningoencephalitis

Chronic lymphocytic leukemia involves the skin in a small percentage of patients and may portend an ominous prognosis in some patients. We report a series of eight biopsies from seven different patients in which the cutaneous leukemic infiltrate was confined exclusively to the region immediately surrounding primary epithelial neoplasms including squamous cell carcinoma (6), basal cell carcinoma (1) and actinic keratosis (1). The malignant lymphocytes appear to constitute a host response to these neoplasms and do not appear to suggest a rapid downhill course for these patients. These observations serve to 1) suggest a new pattern of cutaneous involvement by leukemic cells and 2) offer some insights into potential cellular trafficking patterns of these neoplastic cells.     

Prostaglandins increase matrix metalloproteinase release from human ciliary smooth muscle cells

PURPOSE: To identify matrix metalloproteinases (MMPs) released by ciliary smooth muscle cells in vitro and to determine whether MMP release is altered by exposure to prostaglandins (PGs). METHODS: Human ciliary smooth muscle cells were grown to confluence in monolayer cultures and treated with PGF2 alpha, 11-deoxy-PGE1, or PhXA85 (the nonesterified analogue of PhXA41) for 12 to 72 hours. The activity of MMP in the medium was assayed using gelatin and casein zymography. Identification of the specific MMP associated with each band was made by Western blot analysis. Band intensity, which reflects activity, was measured with a scanning laser densitometer. RESULTS: Three major bands appeared in the gelatin zymographs at positions corresponding to molecular weights of 62 kDa, 68 kDa, and 97 kDa. A single band at 50 kDa predominated in the casein zymograms. Substitution of EDTA for calcium and zinc in the development solution eliminated the appearance of these bands, indicating that they reflect MMP activity. Immunoblotting, using MMP-specific antibodies, confirmed that the three bands in the gelatin zymographs were MMP-1, MMP-2, and MMP-9, respectively; the single band in the casein zymographs was MMP-3. Treatment with 200 nM PGF2 alpha, 11-deoxy-PGE1, or PhXA85 for 72 hours increased the combined density scores for MMP-1 and MMP-2 by 37%, 64%, and 27%; the density scores for MMP-9 by 268%, 253%, and 125%; and the density scores for MMP-3 by 35%, 71%, and 22%, respectively. CONCLUSIONS: These results indicate that ciliary smooth muscle cells can secrete MMP-1, MMP-2, MMP-3, and MMP-9. In addition, exposure to PGF2 alpha, 11-deoxy-PGE1, or PhXA85 increases production of all four MMPs. These observations support the hypothesis that increased MMP production by ciliary muscle cells has a role in increasing uveoscleral outflow facility after topical PG administration.     

Social inhibition of territorial behaviour in yearling male collared lizards, Crotaphytus collaris

The myenteric plexus was investigated in the gastrointestinal tract of pre-diabetic and diabetic non-obese diabetic (NOD) mice. The plexus was immunostained by the avidin-biotin complex method, using a general marker for nerve elements, namely protein gene-product 9.5. The nerve fibres were quantified by point-counting and the number of ganglia and their area were determined by image analysis. The relative volume density of the nerve fibres in duodenal muscularis propria was found to be significantly reduced in of both pre-diabetic and diabetic NOD mice. There was no statistical difference between controls and NOD mice regarding relative volume density of nerve fibres in antral and colonic muscularis propria. The number of myenteric ganglia/mm baseline was significantly decreased in the duodenum of diabetic NOD mice, and showed a non-statistically significant tendency to decrease in pre-diabetic mice. In the antrum and colon, there was no difference between the controls and NOD mice regarding the number of ganglia/mm baseline. Nor was there any significant difference between controls and NOD mice in the area of myenteric ganglia in either antrum, duodenum or colon. It is concluded that the changes in the duodenal myenteric plexus of NOD mice are prior to the onset of diabetes. It is suggested that the absence of changes in the antral and colonic myenteric plexus when using a general marker for neuroelements does not preclude a possible change in cholinergic, adrenergic or peptidergic innervation.     

Skeletal-unit growth in the mandible of rats given diphenylhydantoin

With the purpose of studying the effect of diphenylhydantoin on mandibular skeletal-unit growth, 28 male Wistar rats weighing 60.0 +/- 0.8 g were assigned to five different groups. One group received saline serving as normal controls; three others were injected intra peritoneally once daily with either 25, 50 or 100 mg/kg body wt diphenylhydantoin for 30 days; the fifth group was put on a restricted diet (20% below normal intake) for the same time. On day 31, the rats were killed by ether overdose and their mandibles were evaluated for differential skeletal-unit growth. Body-weight gain of diphenylhydantoin-injected rats was up to 24% less than controls, regardless of drug dose. Diet-restricted rats showed a similar difference. The amount of food consumed by diphenylhydantoin-injected rats was 21% less than that consumed by controls, regardless of drug doses. The concentration of alkaline phosphatase and haemoglobin in rats treated with 50 or 100 mg/kg diphenylhydantoin was lower than in controls and diet-restricted rats. However, plasma urea and total calcium were similar in diphenylhydantoin-treated rats and controls. Mean appetite quotient, and the efficiency of protein and energy utilization, did not appear to change in response to the particular diphenylhydantoin dose or to the restricted diet. Mandibular dimensions of rats injected with 25 or 50 mg/kg diphenylhydantoin were not statistically different from those of the control and diet-restricted groups. With using 100 mg/kg diphenylhydantoin for 30 days, the growth of symphysial and basal heights, condylar and angular lengths and condylar width was significantly less than in the control and diet-restricted groups. The remaining mandibular skeletal units did not exhibit significant differences from those of control and diet-restricted rats. The disharmonious growth of the mandible does not appear to depend on suboptimal energy intake, efficiency of protein-energy utilization, renal failure and anaemia, but would suggest a differential toxicological effect of diphenylhydantoin on the osseous component and/or its associated non-skeletal tissues.