Pharmacokinetic study of meropenem in healthy beagle dogs receiving intermittent hemodialysis

Meropenem, a second carbapenem antimicrobial agent with a broad spectrum of activity, is used to treat sepsis and resistant‐bacterial infections in veterinary medicine. The objective of this study was to identify the pharmacokinetics of meropenem in dogs receiving intermittent hemodialysis (IHD) and to determine the proper dosing in renal failure patients receiving IHD. Five healthy beagle dogs were given a single i.v. dose of 24 mg/kg of meropenem and received IHD. The blood flow rate, dialysate flow, and ultrafiltration rate were maintained at 40 mL/min, 300 mL/min, and 40 mL/h, respectively. Blood samples were collected for 24 h from the jugular vein and from the extracorporeal arterial and venous line. Urine samples and dialysate were also collected. The concentrations of meropenem were assayed using HPLC/MS/MS determination. The peak plasma concentration was 116 ± 37 μg/mL at 15 min. The systemic clearance was 347 ± 117 mL/h/kg, and the steady‐state volume of distribution was 223 ± 67 mL/kg. Dialysis clearance was 71.1 ± 34.3 mL/h/kg, and the extraction ratio by hemodialysis was 0.455 ± 0.150. The half‐life (T_1/2) in dogs with IHD decreased compared with those without IHD, and the reduction in T_1/2 was greater in renal failure patients than in normal patients. Sixty‐nine percent and 21% of the administered drug were recovered by urine and dialysate in the unchanged form, respectively. In conclusion, additional dosing of 24 mg/kg of meropenem after dialysis could be necessary according to the residual renal function of the patient based on the simulated data.     

Treatment of porcine oocytes with MEM vitamins during in vitro maturation improves subsequent blastocyst development following nuclear transfer

This study was carried out to investigate the effects of minimum essential medium (MEM) vitamins during in vitro maturation (IVM)/in vitro culture (IVC) of porcine nuclear transfer (NT) embryos on subsequent developmental capacity in vitro. Porcine cumulus-oocyte complexes (COCs) were divided into five groups, matured for 44 h in maturation medium with various concentrations of MEM vitamins (0, 0.05, 0.1, 0.2 and 0.4%), and observed for maturation rate. Also, COCs were matured in NUSU-23 media without MEM vitamins for 44 h and cultured in PZM-3 media with various concentrations of MEM vitamins (0, 0.05, 0.4 and 1.0%) for 6 days following nuclear transfer. Factorial (IVM/IVC) experiments were also performed in NCSU-23 medium with or without 0.05% MEM vitamins and PZM-3 medium with or without 0.4% MEM vitamins. They were then tested by examining in vitro development of the porcine reconstructed embryos. The maturation rates of the COCs treated with the MEM vitamins did not differ significantly among the MEM vitamin-treated groups. Addition of vitamins to culture medium did not affect development of porcine reconstructed embryos in vitro. However, addition of low concentrations of MEM vitamins only to maturation medium increased (P<0.05) the proportion of NT embryos developing into blastocysts compared with the control group. Addition of MEM vitamins to IVC medium did not enhance the developmental rate compared with the control group. Thus, addition of MEM vitamins to IVM medium could improve subsequent blastocyst development of porcine NT embryos.     

Comparison of water status indicators for young peach trees

We measured a series of physiological and physical indicators and compared them to xylem sap flow, to identify the most sensitive and reliable plant water status indicator. In the growing season of 1998, 4-year-old peach trees (Prunus persica Batsch cv. 'Suncrest', grafted on 'GF 677' rootstock) were studied under two irrigation treatments, 25 l day^у and no irrigation, and during recovery. Trials were conducted near Pisa (Italy) in a peach orchard situated on a medium clay loam soil and equipped with a drip-irrigation system (four 4 l h^у drippers per tree). Measurements of leaf water potential (ƒ_W), stem water potential (ƒ_S), and leaf temperature (T_l) were taken over 5 days (from dawn to sunset) and analyzed in conjunction with climatic data, sap flow (SF), trunk diameter fluctuation (TDF) and soil water content (SWC). Physiological indicators showed substantial differences in sensitivity. The first indication of changes in water status was the decrease of stem radial growth. TDF and SF revealed significant differences between the two irrigation treatments even in the absence of differences in pre-dawn leaf water potential (pdƒ_W), up until now widely accepted as the benchmark of water status indicators. Irrigated trees showed a typical trend in SF rate during the day, while in non-irrigated plants the maximum peak of transpiration was anticipated. Measurements of water potential showed ƒ_S to be a better indicator of tree water status than ƒ_W. T_l was found to have poor sensitivity. In conclusion, we found the sensitivity of the indicators from the most to the least was: TDF >SF rate >SF cumulated = pdƒ_W=ƒ_S>mdƒ_W>T_l.     

Controlled water table management as a strategy for reducing salt loads from subsurface drainage under perennial agriculture in semi-arid Australia

Recent community based actions to ensure the sustainability of irrigation and protection of associated ecosystems in the Murrumbidgee Irrigation Area (MIA) of Australia has seen the implementation of a regional Land and Water Management Plan. This aims to improve land and water management within the irrigation area and minimise downstream impacts associated with irrigation. One of the plan objectives is to decrease current salt loads generated from subsurface drainage in perennial horticulture within the area from 20 000 tonnes/year to 17 000 tonnes/year. In order to meet such objectives Controlled Water table Management (CWM) is being investigated as a possible ‘Best Management Practice’, to reduce drainage volumes and salt loads.During 2000–2002 a trial was conducted on a 15 ha subsurface drained vineyard. This compared a traditional unmanaged subsurface drainage system with a controlled drainage system utilizing weirs to maintain water tables and changes in irrigation scheduling to maximize the potential crop use of a shallow water table. Drainage volumes, salt loads and water table elevations throughout the field were monitored to investigate the effects of controlled drainage on drain flows and salt loads.Results from the experiment showed that controlled drainage significantly reduced drainage volumes and salt loads compared to unmanaged systems. However, there were marked increases in soil salinity which will need to be carefully monitored and managed.     

Potato evapotranspiration and yield under different drip irrigation regimes

A field experiment comparing different irrigation frequencies and soil matric potential thresholds on potato evapotranspiration (ET), yield (Y) and water-use efficiency (WUE) was carried out in a loam soil. The experiment included five treatments for soil matric potential: F1 (-15 kPa), F2 (-25 kPa), F3 (-35 kPa), F4 (-45 kPa) and F5 (-55 kPa) and six treatments for irrigation frequency: N1 (once every day), N2 (once every 2 days), N3 (once every 3 days), N4 (once every 4 days), N6 (once every 6 days) and N8 (once every 8 days). Results indicate that both soil matric potential and drip irrigation frequency influenced potato ET, Y and WUE. Potato ET increased as irrigation frequency and soil matric potential increased. Comparing soil water potential, the highest ET was 63.4 mm (32.1%) more than the lowest value. Based on irrigation frequency treatments, the highest ET was 36.7 mm (19.2%) more than the lowest value. Potato Y and WUE were also found to increase as irrigation frequency increased. Potato Y increased with an increase in soil water potential then started to decrease. The highest Y and WUE values were achieved with a soil matric potential threshold of -25 kPa and an irrigation frequency of once a day.Communicated by J. Ayars     

Malignant transformation of a unicameral bone cyst in a cat

A unicameral bone cyst in the proximal humerus of a 3-year-old Norwegian forest cat was diagnosed by dynamic contrast-enhanced magnetic resonance imaging, surgical exploration, and histopathology. Surgical curettage and incorporation of bone cement led to full recovery. An osteosarcoma developed at the surgical site 17 months later. Thoracic radiographs showed pulmonary lesions consistent with metastasis.     

Metabolic differentiation of bloodstream forms of Trypanosoma brucei brucei into procyclic forms. Effect of hydroxyurea, arabinosyl adenine, and serum omission

Bloodforms of Trypanosoma brucei brucei STIB 247 taken from rats and containing more than 80 per cent short stumpy forms, differentiated in vitro to procyclic forms in medium SDM 79 (Brun and Sch?nenberger 1979), enriched with 3 mmol.dm-3 cis-aconitate. Cell division was abolished by the addition of hydroxyurea (200 micrograms.ml-1) or arabinosyl adenine (20 micrograms.ml-1 to the cultivation medium, or by the omission of serum from the medium. The ultrastructure of exponentially growing controls was rearranged within 24 h. The endogenous respiration and the respiration stimulated by proline, succinate, and 2-oxoglutarate were detectable within 12 h; after 48 h the respiration rates were comparable to those found in the established procyclic forms. After 12 h the respiration was inhibited by 200 mumol.dm-3 KCN, and by 20 mumol.dm-3 antimycin to the extent found in procyclic forms. Hydroxyurea did not significantly affect respiration. Activities of procyclic-stage enzyme markers malate dehydrogenase, threonine dehydrogenase, succinate: cytochrome c reductase, and NADH: cytochrome c reductase rose within 48 h of differentiation to values which were close to those found in established procyclic forms. The activity of glutamate dehydrogenase (NAD-specific), however, was only 1/3 of that in the procyclics, and no citrate synthase was detected in differentiating culture. Glycosomal malate dehydrogenase was detected after 6 h. In the presence of hydroxyurea or arabinosyl adenine, or in the absence of serum, respiration rates, marker enzyme activities, and glycosomal malate dehydrogenase developed to the extent comparable to the untreated controls. The results suggest that it is possible to separate the process of differentiation from cell proliferation. Cell division is not a necessary prerequisite of differentiation.     

Ultrastructure of the excretory system of Brachylaimus aequans (Trematoda: Brachylaimoidea)

The ultrastructure of the flame cell, excretory capillaries, ducts, collecting ducts, excretory bladder, and excretory pore of Brachylaimus aequans was studied 6-8 days p.i. The excretory ducts, collecting ducts and excretory bladder are provided with numerous lamellae on the luminal side. The cilia of lateral flames in the excretory ducts have a triated rootlet. The excretory pore is covered by a tegument identical with the body tegument. The syncytium of the excretory bladder is connected with the tegument of the excretory pore by means of a septate desmosome. No lipid or excretory corpuscles have been demonstrated in the excretory system.     

Entamoeba histolytica--the virulence of imported strains

We tested the virulence of 15 strains of Entamoeba histolytica, imported to Czechoslovakia, by intracaecal inoculation of laboratory rats. According to the scoring system of Neal, none of the 15 strains possessed the virulence index greater than 2. This indicates that all the organisms tested should be classified as avirulent. However, it should be noted that all the strains produced infection of the caecum and thus should be considered infective for rat. For 7 strains, isoenzyme patterns were determined for PGM, HK and ME. One imported strain, obtained from student from Congo, demonstrated isoenzyme pattern for PGM and HK indicated that the strain was virulent. This organisms had the index of virulence 1.8 (avirulent) in animal experiment; it was isolated from cysts of clinically asymptomatic patient. Examination of the rectal mucosa of the donor of the strain indicated typical chronic catarrhal proctitis of mild degree. Examination of the patient's serum demonstrated the presence of anti E. histolytica antibodies by CIEP, while the ELISA test was negative. Twenty-one cyst carriers were examined by rectoscopy. Pathologic changes were observed in 20 of these, as follows: altered vascular structure (13X), roughened mucosa (12X), mucosal reddening (10X), decreased glistening (7X), mucus in mucosa (5X), inflammatory pseudopolypes (2X), ulcers (2X), enanthema (1X). Histological biopsies were obtained in 15 cases. One was considered normal. Remaining 14 biopsies exhibited following morphological changes: increased mucus secretion (8X), edema (7X), lymphocytic and plasmocytic infiltration (6X), lymphocytic and plasmocytic infiltration in addition to the presence of eosinophilic granulocytes (6X), presence of mucophages (5X), haemorrhages (4X), increased vascularity (3X), lymphocytic and plasmocytic infiltration with presence of extremely abundant eosinophilic granulocytes (1X), erosive-ulcerative changes of mucosa (1X). The changes observed indicated chronic catarrhal proctitis with expression to greater or less degree of signs of chronic catarrhal inflammation.     

Colonization of Ascaris lumbricoides eggs by the fungus Verticillium chlamydosporium Goddard.

The process of colonization of Ascaris lumbricoides eggs by the fungus Verticillium chlamydosporium was studied by scanning electron microscopy. The preparations were made by fractionation of egg suspension exposed to the fungus for four days and frozen in liquid nitrogen according to St?rba and Milácek (1986). Ovicidal fungus forms an abundant ramifying mycelial network in the area between the eggs. However, egg-shells are penetrated only by some hyphae without any penetration organs produced (simple hyphal penetration). In a liquid medium, after penetration, hyphae inside the eggs rapidly grow among inner structures of egg-shells and on the surface of developing larvae. In the next phase, hyphae colonize the developing larva. The eggs attacked by this fungus remain morphologically unchanged for a long time except the sites of penetration. Verticillium chlamydosporium is a fungus with unique ovicidal properties. It colonizes the eggs of Ascaris lumbricoides at all stages of embryo development and also attacks larvae inside the eggs.