Multimodality (auditory, visual and somatosensory) evoked potentials in the sand rat, Psammomys obesus

Multimodality (auditory, visual and somatosensory) evoked potentials were recorded in the sand rat (Psammomys obesus) and compared to those obtained in albino rats, under almost identical conditions. Clear responses could be obtained from each species. The evoked potentials from the sand rat were qualitatively similar in waveform, latency and amplitude to those recorded in albino rats. Since there is a strain of sand rat which develops diabetes when on standard chow and since the sand rat has adapted to the desert environment, further study should involve evoked potential recordings in sand rats during hyper- and hypothermia and in diabetic sand rats.     

Distribution of atrial natriuretic peptides in the sand rat (Psammomys obesus) in comparison to that in the rat

Atrial natriuretic peptides (ANP) are a family of humoral compounds involved in water and salt homeostasis. Immunoreactive ANP (IR-ANP) was determined in the plasma and tissues of the rat and the sand rat (Psammomys obesus) using sensitive and specific radioimmunoassay. IR-ANP from the rat and the sand rat elute at identical retention times from reverse phase HPLC indicating that the same chemical entity is present in both species. IR-ANP highest levels were found, in both species, in the heart but it was also present in the adrenal gland, lung, kidney, liver, plasma and several loci in the central nervous system. The IR-ANP levels in the heart, adrenal gland, kidney, liver, cerebellum and cerebral cortex were lower in the sand rat compared to the rat. The plasma IR-ANP level of the diabetes-resistant sand rat was further decreased to about 10% of the level in the diabetes-resistant sand rat.     

Effects of obesity and inheritance on the development of non-insulin-dependent diabetes mellitus in Otsuka-Long-Evans-Tokushima fatty rats

Schistosomiasis constitutes one of the major endemic diseases in both African and Asian countries. There are numerous strains of Schistosoma mansoni. Although there is similarity between their life cycles, yet there are many differences in the morphology of the adult worms, their pathogenecity, their infectivity and their ultrastructural features. This study was performed on albino mice infected with both Egyptian and Saudi strains, to investigate the characteristic differences between them. It was found that at the eight week post-infection, the highest amount of egg deposition and granuloma formation was present in the liver of infected mice with the Egyptian strain; while it was highest in the small intestine of those infected with the Saudi strain, followed by the liver and the large intestine. Although no prominent histopathologic differences were detected in the cellular and tissue reactions in the resulting granulomata surrounding eggs, yet marked differences were observed in the surface topography of the tegument and distribution of papillae, pattern of ridges, microvilli, and spines of both strains. These differences were more pronounced in males. It might be concluded from this study that such differences are due to strain variation, biological and morphological characteristics of Schistosoma mansoni, and could be considered as a baseline for further experimental studies.     

Enhanced de novo lipogenesis in the leptin-unresponsive pancreatic islets of prediabetic Zucker diabetic fatty rats: role in the pathogenesis of lipotoxic diabetes

Overaccumulation of fat in pancreatic islets of obese ZDF fa/fa rats is believed to cause beta-cell failure and diabetes. Previously, we demonstrated that ZDF islets have an increased capacity to esterify fatty acids imported via the circulation. Here we examine the capacity of ZDF islets to synthesize fatty acids de novo. Compared with age-matched wild-type (+/+) control islets, acetyl CoA carboxylase (ACC) mRNA was fivefold and sixfold higher and fatty acid synthetase (FAS) was fourfold and sevenfold higher in prediabetic and diabetic ZDF islets, respectively. Incorporation of label from [14C]glucose into lipids was 84% higher in ZDF islets and was not suppressed normally by fatty acids. Chronic hyperleptinemia, induced by adenoviral transfer of leptin cDNA, reduced ACC and FAS mRNA in +/+ islets by 93 and 80%, respectively, but did not decrease the high ACC and FAS expression in islets of fa/fa rats. Recombinant leptin cultured with islets isolated from +/+ rats lowered ACC and FAS expression by 66 and 47%, respectively, but had no effect in fa/fa islets. We conclude that de novo lipogenesis in islets is controlled by leptin and remains low in leptin-responsive islets. It is increased in leptin-insensitive fa/fa islets, contributing to the fat overload that leads to beta-cell dysfunction and diabetes.     

The development of overt diabetes in young Zucker Diabetic Fatty (ZDF) rats and the effects of chronic MCC-555 treatment

1. Young (6-week-old) pre-diabetic Zucker Diabetic Fatty (ZDF) rats displaying impaired glucose tolerance (IGT), moderate hyperglycaemia and hyperinsulinaemia were treated with the novel thiazolidinedione, MCC-555, for 28 days, during which time beta-cell failure and progression to overt diabetes occurs. 2. Treated ZDF rats exhibited consistently lower blood glucose levels than vehicle-treated diabetic controls, with a delayed rise and lower plateau levels. MCC-555 maintained plasma insulin levels throughout the treatment period, whereas these fell by 40% in untreated ZDF rats. 3. The rise in body weight was maintained in MCC-555-treated rats, whereas vehicle-treated rats exhibited blunted body weight gain after 8 weeks of age. Daily food intake was higher in diabetic, as compared to non-diabetic rats, but treatment did not modify food intake in diabetic rats. Water intake was lower in treated ZDF rats, concomitant with lowering of blood glucose. 4. The hyperinsulinaemic-euglycaemic clamp technique was applied to all rats after treatment to examine the effects of MCC-555 on insulin sensitivity. The glucose infusion rate to maintain normoglycaemia was lower in diabetic than in non-diabetic rats, demonstrating reduced glucose entry into insulin-sensitive tissues in diabetic rats. Increased glucose infusion rates were required to maintain euglycaemia in treated diabetic rats, demonstrating increased insulin sensitivity in these animals. 5. In conclusion, chronic MCC-555 treatment of young ZDF rats displaying IGT attenuates the development of overt diabetes through improved insulin sensitivity and maintenance of beta-cell function. MCC-555 may thus be beneficial in humans with IGT, to prevent or delay the progression of diabetes.     

The role of cellular degeneration in the normal development of (rat) otocyst

From day 12 to 16 of gestation a highly circumscribed zone of cellular degeneration has been observed in the otocyst of more than 50 normal rats. This zone appears to be produced by selective or programmed cell death, and results in the elimination of unneeded cellular elements. That cells in this zone are also selectively destroying subcellular organelles as a first step in specialization is also discussed. Programmed cellular death has long been known in other systems and is often an obligatory companion to cellular specialization. The ear now joins the long list of organs which demonstrate this phenomenon.     

The role of laparoscopy in the treatment of morbid obesity

The protective effect of ceftriaxone on isepamicin-induced nephrotoxicity was investigated. For 14 d, Wistar rats were administered either ceftriaxone 100 mg/kg intraperitoneally, isepamicin 300 mg/kg subcutaneously, or ceftriaxone isepamicin in combination. The animals given 300 mg/kg of isepamicin showed a significant increase in urine NAG (N-acetyl-beta-D-glucosaminidase) levels as compared with the control animals which received saline (p<0.01). However, the increase in NAG level was markedly less when isepamicin was administered in combination with ceftriaxone (p<0.01). Ceftriaxone alone had no effect on urine NAG activity. Serum creatinine levels were significantly higher in animals treated with isepamicin alone than in control animals (p<0.01) or animals receiving the isepamicin ceftriaxone combination (p<0.01). After 14 d of treatment, ceftriaxone had not accumulated in renal tissue, but it did reduce the renal intracortical accumulation of isepamicin (p<0.01). Histopathologically, ceftriaxone induced very few cellular alterations and considerably reduced the manifestation of typical signs of isepamicin nephrotoxicity. This investigation demonstrates that ceftriaxone protects animals against isepamicin-induced nephrotoxicity.     

The role of dopaminergic and serotonergic mechanisms in the development of swimming ability of young rats

Neonatal swimming behavior was studied after a single subcutaneous injection of L-dopa methyl ester (50 mg/kg; 200 mg/kg) apomorphine (0.1 mg/kg; 1.0 mg/kg), DL-amphetamine (0.5 mg/kg; 10 mg/kg), haloperidol (0.5 mg/kg; 1.0 mg/kg), L-tryptophan (50 mg/kg; 100 mg/kg), methysergide (1.0 mg/kg; 5.0 mg/kg) as well as intraventricular injection of 100 microgram 6-OHDA. 1-, 3-, 5- and 7-day-old rats were placed into a temperature-controlled aquarium (37 degrees C) and the pattern of motor coordination, latency time to swimming (LTS) and the number of foreleg strokes for 10 s (FS) were measured. When compared to the physiological saline-injected controls, rats that received L-dopa showed a striking increase of FS at all ages but the most striking improvement of motor coordination was found in newborn rats. On day 1 both doses of DL-amphetamine induced increases in FS and improvement of motor coordination, whereas apomorphine failed to show any effect at this age. On days 3, 5 and 7 low doses of DL-amphetamine and apomorphine increased the FS. However, high doses resulted in a decrement in swimming performance. Haloperidol impaired swimming on day 1 but produced a significant increase of FS on days 5 and 7. Neonatal injection of 6-OHDA delayed development of motor coordination, reduced FS and increased LTS. On days 3, 5 and 7 high doses of L-tryptophan elicited an increase of FS, while high doses of methysergide caused significant impairment of performance. It is suggested that the brain rapidly converts the administered L-dopa to dopamine during the first week of life and there appears to be a strong dependent relationship between the pattern of motor coordination and the amount of available dopamine in the developing brain.     

The dietitian''s role in developing and implementing the first federal obesity guidelines

OBJECTIVE: To determine possible indications for tracheotomy in the burned child based on bronchoscopic and laryngoscopic findings. DESIGN AND SETTING: A retrospective case study of all patients admitted to a tertiary children's burn center. PARTICIPANTS: All children admitted with burn inhalation injury between 1990 and 1995 (n = 211). INTERVENTION: All patients underwent laryngoscopy and bronchoscopy and 19 underwent tracheotomy, with 5 tracheotomy tubes placed emergently. MAIN OUTCOME MEASURES: Observations during laryngoscopy and bronchoscopy included erythema, edema, carbonaceous material, ulcerations, and bronchial mucous casts. The supraglottis, glottis, and subglottis were analyzed separately, when possible. Any sepsis resulting from tracheotomy was determined. Complications, such as glottic webs, subglottic stenosis, and tracheomalacia, were noted. RESULTS: Indications for tracheotomy included 6 for airway obstruction, 6 for prolonged intubation, 6 for pulmonary cleansing, and 1 for endotracheal tube complications (subglottic stenosis). When examined by bronchoscopy and laryngoscopy, 17 of 19 children had significant airway edema, 10 had carbonaceous material in the airway, and 3 had ulcerations in the airway. CONCLUSIONS: Tracheotomy is indicated in the burned child when significant airway edema is present. Failure to place a tracheotomy tube in these cases leads to a high incidence of immediate tracheotomies (26%). There was no evidence of clinically significant infection attributable to tracheotomy. The number of airway complications due to tracheotomy was no higher than from endotracheal intubation.     

钢包引流砂机械式投放技术的开发应用

针对莱芜钢铁集团有限公司银山型钢有限公司炼钢厂采用人工投放钢包引流砂,导致引流砂大量浪费,增加钢水夹杂,影响水口自开率,制约炼钢生产等问题,通过开发引流砂复合引流器投放工艺技术以及对钢包水口座砖内径进行调整优化等措施,实现了钢包引流砂机械式投放。使水口自开率由95.5%提高到99.2%,吨钢引流砂消耗降低了0.37 kg。     

The role of the research and development officer

This article describes some of the barriers to professional development and discusses how research and development (R&D) officers can overcome these and support their colleagues in clinical practice.     

A newly discovered role of transcription factors involved in pancreas development and the pathogenesis of diabetes mellitus

BACKGROUND: Functional vision loss is a general term used to describe vision loss not associated with organic disease. Such cases are major challenges to the practitioner and demand a special workup. METHODS: Patients may manifest symptoms in typical ways that should alert the examiner to the possibility of functional vision loss. In addition, a variety of techniques help distinguish functional from organic causes of vision loss. These techniques include standard tests that yield characteristic findings in functional vision loss, as well as problem-specific procedures that have the specific aim of detecting functional vision loss. Techniques are described according to whether they are useful in monocular or binocular vision loss and in cases of moderate or severe vision loss. RESULTS: Three cases that illustrate the use of standard and select techniques to detect functional vision loss are presented. Differential diagnosis of functional from organic vision loss and special considerations in the management of patients with functional vision loss are also discussed. CONCLUSIONS: Although it is necessary to rule out underlying pathology in all cases of vision loss, a variety of techniques can provide positive evidence of functional vision loss.     

The role of melatonin in the human fetus (review)

Melatonin, an indole amine, primarily derived from the pineal gland is secreted during the hours of darkness. Melatonin acts as a hormonal transduction of photoperiod influencing the timing of seasonal and daily (circadian) physiological rhythms. Maternal melatonin crosses the placenta and enters the fetal circulation providing photoperiodic information to the fetus influencing the subsequent circadian and seasonal rhythms of the offspring. The function of melatonin in humans is more obscure. However, melatonin has attained prominence as a treatment for disturbed circadian rhythms and sleep patterns which occur as a result of transmeridian travel, shift work or blindness. The biological clock, the hypothalamic suprachiasmatic nuclei (SCN), possesses melatonin receptors, in both the adult and fetal human. This concurs with the reported influence of melatonin on human circadian rhythmicity and indicates that this influence may begin in utero. Melatonin receptors are widespread in the human fetus and occur in both central and peripheral tissue from early in fetal development. Thus, the influence of melatonin on the developing human fetus may not be limited to entraining circadian rhythmicity. Considering the transplacental availability of melatonin to the fetus the ingestion of melatonin by pregnant women may be inadvisable.