Degradation of Weathered Oil by Mixed Marine Bacteria and the Toxicity of Accumulated Water-Soluble Material to Two Marine Crustacea

Artificially weathered crude oil was degraded by four diverse cultures of mixed marine bacteria under optimized conditions for 7 and 14 days. Loss in total weight of starting oil (30 g) ranged from 6.8–17.3% in biologically active incubations compared with only 0.9–1.1% in sterile and nutrient-limited controls. In all incubations, both neutral and acidic water-soluble fractions (WSF) were accumulated. In biologically active systems, 50.9–249.0 mg neutral and 63.3–406.8 mg acidic WSF were accumulated whereas only 6.5–11.1 mg neutral and 1.7–2.2 mg acidic WSF were accumulated in control incubations. Analysis by gas chromatography demonstrated that accumulated WSF in biologically active systems contained compounds different from those washed from the starting crude oil. Exposure of grass shrimp (Palaemonetes pugio) embryos to neutral WSF from each of the biologically active cultures resulted in high embryo mortalities relative to sterile and nutrient-limited controls which exhibited >90% hatching success and larval survival. Toxicity of neutral WSF was also demonstrated on larvae of mysids (Mysidopsis bahia). In both cases, toxicity occurred only on exposure to neutral material accumulated by active, oil-degrading cultures and not with material washed from the weathered crude oil. These results imply that unique compounds were accumulated during degradation that may have been responsible for increased toxicity. Received: 23 December 1997/Accepted: 27 July 1998     

Cardiac function and morphology studied by two-dimensional Doppler echocardiography in unsedated newborn pigs

The newborn pig is currently the most used species in animal neonatal research. Valid non-invasive monitoring is important in particular for long-term survival of unsedated animals. In the unsedated newborn pig (n = 35, median age 24 h, range 7-48 h) we standardized two-dimensional Doppler echocardiography and determined the normal ranges for cardiac function. Probe positioning had to be adjusted to the V-shaped thorax and the mid-line position of the heart. Six out of the sixteen animals < 20 h had a patent ductus arteriosus compared with one of the twenty animals > 20 h old. One atrial septal defect (5 mm) and one small ventricular septal defect were diagnosed. The average heart size was 0.7-0.9% of body weight which is similar to human infants of the same size. The mean aortic diameter was 6.0 +/- 0.5 mm (mean +/- S.D.) and cardiac output was 0.38 +/- 0.08 l min-1; both correlate with body weight (r = 0.80 and 0.73, respectively). Tricuspid regurgitation velocity was 3.0 +/- 0.4 m s-1 (mean +/- S.D.), giving an estimated pressure gradient across the tricuspid valve of 37 +/- 9.7 mmHg. The aortic diameter and the heart weight per kg body weight are comparable to those reported for preterm neonates. The cardiac output and velocities across the four valves are more comparable with term neonates.     

Effects of the superoxide dismutase-mimic compound TEMPOL on oxidant stress-mediated endothelial dysfunction

The aim of this study was to investigate the effects of oxidant stress on endothelium-dependent and endothelium-independent arterial relaxation. For this, oxidant stress was generated by preincubation of rat aortic rings (RARs) in either 25 mM glucose (mimicking hyperglycemic stress) or 0.5 mM pyrogallol (a superoxide generator) and the effects of the superoxide dismutase (SOD)-mimetic compound 4-hydroxy-2,2,6,6-tetramethylpiperidinyloxy free radical (TEMPOL) on the vasorelaxant and cGMP-producing effects of acetylcholine (ACh) and glyceryl trinitrate (GTN) in control RARs and RARs exposed to oxidant stress were examined. Pyrogallol, and to a lesser extent high glucose concentration, enhanced the contractile response of RARs to phenylephrine and markedly inhibited the vasorelaxant response to ACh. Although they existed, the inhibitory effects of high glucose and pyrogallol on the vasorelaxant response to GTN were less profound, especially with pyrogallol. Moreover, both pyrogallol and high glucose concentration inhibited the basal and the ACh-induced vascular cyclic guanosine monophosphate (cGMP) production. Treatment with TEMPOL (1-5 mM) slightly increased the ACh and GTN-induced cGMP levels in control RARs but had a significant effect in high glucose and pyrogallol-pretreated RARs. Additionally, concomitant treatment of RARs with TEMPOL (5 mM) abolished the difference in the relaxation response between control RARs and RARs exposed to either pyrogallol or high glucose concentration. These results further support the theory that reactive oxygen species (ROS), especially superoxide, play a key role in mediation of endothelial dysfunction accompanying diabetes, probably through their effects on the ability of the endothelium to synthesize, release or respond to endogenous nitric oxide (NO) or NO donated by nitrovasodilators.     

How to interpret differing cerebral blood flow patterns estimated with 99Tcm-HMPAO and 99Tcm-ECD SPET in a healthy population

Two radiopharmaceuticals, 99Tcm-hexamethyl propylene amine oxime (99Tcm-HMPAO) and 99Tcm-ethyl cysteinate dimer (99Tcm-ECD), are currently used to determine cerebral blood flow. 99Tcm-ECD is, by virtue of its greater stability, superseding 99Tcm-HMPAO for routine examinations. Since the clinical assessment of 99Tcm-ECD images is usually based on experience with 99Tcm-HMPAO, we used both radiopharmaceuticals to compare regional cerebral blood flow in the same individuals. Eleven healthy subjects aged 67.1 +/- 6.3 years (mean +/- S.D.) underwent 99Tcm-ECD followed by 99Tcm-HMPAO single photon emission tomography. Cerebral blood flow was quantified in cortical and central regions of interest (basal ganglia, ventricles, white matter) in relation to cerebellar uptake. The intra-subject comparison of cerebral blood flow in the cortical areas revealed higher levels of perfusion in the posterior parietal, parieto-occipital and temporo-occipital areas using 99Tcm-ECD. In contrast to the cortical areas, cerebral blood flow in the central areas was greater using 99Tcm-HMPAO, especially in the centrum semiovale, basal ganglia, frontal white matter and frontal horns. This difference in cerebral blood flow when imaging healthy individuals with 99Tcm-ECD and 99Tcm-HMPAO should be taken into account in clinical practice when changing from one radiopharmaceutical to the other.     

Early muscle-periosteal lesion inhibits fracture healing in rats

We assessed the effects of muscular detachment from the periosteum on fracture healing, focusing on a muscle-periosteal lesion in the initial healing process. In 30 male Wistar rats we produced a partial osteotomy in the mid-diaphysis of the left femur which was then manually broken. All fractures were reamed and stabilized with a 1.6 mm steel pin. The animals were randomly assigned to 3 groups. In group 1, an extraperiosteal detachment between muscle and periosteum was created in the middle third of the diaphysis. In group 2, an extraperiosteal detachment was created with application of an ePTFE sheath (Gore-Tex expanded polytetrafluoroethylene) around the shaft between muscle and periosteum during the first 2 weeks following fracture. In group 3, the dissection was identical, while the ePTFE sheath was installed after 2 weeks. The rats were killed after 4 weeks, and their bones were evaluated radiographically and mechanically by the three-point bending test. The fractures healed by production of external callus, and radiographs revealed various degrees of periosteal callus with a radiolucent fracture line, most evident after early muscle-periosteal isolation. The callus area was significantly smaller after early muscle isolation, compared to extraperiosteal dissection alone and later tissue isolation. Bending moment and stiffness were also less in this group than in groups 1 and 3, while fracture energy was less than in group 1. No differences in mechanical properties were detected between extraperiosteal dissection alone and late-tissue isolation. This animal study underlines the importance of early muscle-periosteal apposition for fast periosteal healing of diaphyseal fractures.     

Heterogeneous splenic enhancement patterns on spiral CT images in children: minimizing misinterpretation

PURPOSE: To (a) determine the appearances and timing of heterogeneous splenic enhancement at spiral computed tomography (CT) and (b) identify variables influencing heterogeneous splenic enhancement. MATERIALS AND METHODS: Sequential isolevel (24-mAs) CT images of the spleen obtained at 6-second intervals after initiation of contrast material injection in 112 children (mean age, 4.5 years) were reviewed. Heterogeneity characteristics assessed included type, onset, maximum, and resolution. Relationship to variables (injection rate, age, splenomegaly) was assessed with the Fisher exact test. RESULTS: Eighty-one of the 112 patients (72%) had transient heterogeneity: archiform (45 patients), diffuse (25 patients), and focal (11 patients). Mean times were as follows: initial visualization after onset of contrast material injection, 19.2 seconds; maximum heterogeneity, 27.3 seconds; and resolution, 47.4 seconds. Statistically significant relationships were seen between frequency of heterogeneity and injection rate (> or = 1 mL/sec, 82%; < 1 mL/sec, 50% [P = .001]), age (> 1 year, 76%; < or = 1 year, 46% [P = .04]), and splenomegaly (present, 20%; absent, 77% [P = .048]). CONCLUSION: Heterogeneous splenic contrast enhancement is common, has several patterns of appearance, and is predictably encountered during the 70 seconds after the initiation of contrast material injection. Injection rate, age, and presence of splenic disease influence the frequency with which these artifacts are encountered.     

Impact of a preceding striatal excitotoxic lesion and treatment with ciliary neurotrophic factor on striatal graft survival

The survival of grafted embryonic striatal tissue, dissected from the lateral ganglionic eminence, depends on the status of the host striatum. We found significantly larger volumes of surviving graft tissue and of striatal-like tissue (P-zone) within the graft, when the host striatum had been subjected to an excitotoxic lesion prior to transplantation surgery. Concomitantly the numbers of surviving grafted cells, assessed in both cresyl violet-stained sections and in sections stained with an immunohistochemical marker for striatal neurons, increased as compared to when graft tissue was placed in an intact unlesioned striatum. Finally, we examined the impact of treatment of the donor tissue with ciliary neurotrophic factor (CNTF) on graft survival. CNTF has previously been shown to protect striatal neurons against excitotoxic insults both in vitro and in vivo, but it did not improve striatal graft survival when added to the cell suspension prior to implantation.     

Prevalence, incidence and age at onset of psychiatric disorders in Norway

  Background: Increased demands for psychiatric services and increased rates of sickness absence for depression have raised the question of the occurrence of psychiatric disorders in Norway, and whether there is in fact a rising incidence rate. Methods: Between 1989–1991, 2015 and 617 persons participated in a two-phase population study. Phase I comprised screening by the Hopkins Symptom Check List 25 items (HSCL-25), and phase II a diagnostic interview by the Composite International Diagnostic Interview (CIDI), including report of date (year) of the first occurrence of any symptoms, and any consequent diagnosis: Results: A symptom score of 1.75 or more was found in 19.8% of the women and 9.3% of the men by the HSCL-25. Depression, anxiety or somatoform disorder by CIDI was found in 21.5% of the women and 11.5% of the men. The incidence rate increased significantly from 3.3 to 12.8 per 1000 person years from 1930 to 1991. The incidence rate in the year before the interview was 42.6 per 1000 person years. Age of onset became lower. More women became ill, but the illness seemed to last longer in men. A major problem in comparing results between studies is the different concepts and operationalisations of psychiatric illness, and the varying time periods given for estimates. Conclusion: The findings provide evidence of psychiatric illness being a rising and major health problem, but the role of recall bias must be further investigated. Accepted: 19 August 1999     

Effect of intracerebral norepinephrine depletion on outcome from severe forebrain ischemia in the rat

Manipulations of plasma catecholamine concentrations influence outcome from ischemic brain insults. It has been suggested that these effects are mediated by influences on brain catecholamine concentrations. This study examined whether major changes in brain norepinephrine concentrations can alter outcome from severe forebrain ischemia. Sprague-Dawley rats were administered 50 mg/kg i. p. N-(chloroethyl)-N-ethyl-2-bromobenzylamine (DSP-4) or were left untreated (control). One week later, these rats were subjected to either 7 or 8 min of normothermic forebrain ischemia (bilateral carotid occlusion and MABP=30 mmHg) and allowed to recover for 4 days. Histologic damage was then evaluated. In other control and DSP-4-treated animals, hippocampal microdialysate norepinephrine concentrations were measured before, during and after 8 min of forebrain ischemia. Norepinephrine concentrations were also determined in brain homogenates from non-ischemic DSP-treated and control rats. A 95% depletion of norepinephrine was observed in brain homogenates from non-ischemic DSP-4-treated rats compared with control. During ischemia, microdialysate norepinephrine concentrations increased in control but not in DSP-4-treated rats (P=0.002). For plasma, intra-ischemic epinephrine concentrations increased 8-10-fold and returned to baseline values post-ischemia with no differences between groups. Plasma norepinephrine values remained unchanged in both groups. Histologic damage resulting from either 7 or 8 min of ischemia in hippocampal structures, caudoputamen, and neocortex was similar between DSP-4-treated and control groups. This study could not identify any effect of major changes in brain norepinephrine concentrations on ischemic brain damage. These data indicate that peripheral catecholamine effects on near-complete forebrain ischemic outcome are unlikely to be mediated by effects on central catecholamine concentrations.