Experimental strategies to promote functional recovery after peripheral nerve injuries

The capacity of Schwann cells (SCs) in the peripheral nervous system to support axonal regeneration, in contrast to the oligodendrocytes in the central nervous system, has led to the misconception that peripheral nerve regeneration always restores function. Here, we consider how prolonged periods of time that injured neurons remain without targets during axonal regeneration (chronic axotomy) and that SCs in the distal nerve stumps remain chronically denervated (chronic denervation) progressively reduce the number of motoneurons that regenerate their axons. We demonstrate the effectiveness of low-dose, brain-derived neurotrophic and glial-derived neurotrophic factors to counteract the effects of chronic axotomy in promoting axonal regeneration. High-dose brain-derived neurotrophic factor (BDNF) on the other hand, acting through the p75 receptor, inhibits axonal regeneration and may be a factor in stopping regenerating axons from forming neuromuscular connections in skeletal muscle. The immunophilin, FK506, is also effective in promoting axonal regeneration after chronic axotomy. Chronic denervation of SCs (>1 month) severely deters axonal regeneration, although the few motor axons that do regenerate to reinnervate muscles become myelinated and form enlarged motor units in the reinnervated muscles. We found that in vitro incubation of chronically denervated SCs with transforming growth factor-beta re-established their growth-supportive phenotype in vivo, consistent with the idea that the interaction between invading macrophages and denervated SCs during Wallerian degeneration is essential to sustain axonal regeneration by promoting the growth-supportive SC phenotype. Finally, we consider the effectiveness of a brief period of 20 Hz electrical stimulation in promoting the regeneration of axons across the surgical gap after nerve repair.     

Clofarabine-induced acral erythema during the treatment of patients with myelodysplasia and acute leukemia: report of two cases

Acral erythema has been associated with a number of chemotherapeutic agents, but there are no reports of clofarabine-induced acral erythema in the literature. We describe two patients who developed acral erythema after receiving clofarabine. One patient had myelodysplastic syndrome while the other had acute lymphoblastic leukemia.     

The organisation of the Department of Veterinary Services in Malaysia

The Department of Veterinary Services (DVS) in Malaysia was established in 1888 as an agency to control exotic and domestic animal diseases. Over the years, the structure and functions of the organisation have evolved to meet the growing demand for veterinary services. The responsibilities of the Veterinary Services are enshrined in the Constitution of Malaysia. The current organisation of the DVS is structured to achieve the following objectives:---to prevent, control and eradicate animal and zoonotic diseases--to facilitate the growth and development of a strong animal industry--to ensure that animal products for human consumption are wholesome, clean, safe and suitable to be consumed--to facilitate the growth and development of the animal feed industry--to ensure the welfare and well-being of all animals. To meet these objectives the DVS has nine different divisions, as follows: Planning and Evaluation, Epidemiology and Veterinary Medicine, Veterinary Public Health, Research and Development, Industry Development, Production and Development of Genetic Resources, Human Resource Development (HRD), Enforcement, and Administration. The development of the animal industry is managed through national development policies, including the Third National Agriculture Policy. The basis for current programmes for disease control and animal industry development is the Eighth Development Plan (2001-2005). Over the period of this Plan, Malaysia will address the need for sanitary and phytosanitary measures by developing specific programmes covering all fields of the animal industry. This is just one way in which Malaysia is meeting the challenges of the increased liberalisation of trade created by the World Trade Organization and the Association of Southeast Asian Nations Free Trade Area. The development of the industry is focused on the major commodities, namely, beef, mutton, poultry meat, eggs, pork and milk. Other commodities receive support if it is considered economically viable. All support services are being strengthened, particularly the HRD division. The organisation and functions of the DVS are constantly being reviewed in accordance with changes in the animal industry and the nature of the services in demand.     

Effect of lithium on cyclosporin induced nephrotoxicity in rats

Psychoactive drugs provide essential intervention in the care of transplant recipients, yet little is known of their interaction with immunosuppressants such as cyclosporin (CSA). Lithium (Li) is an invaluable drug for the treatment of manic disorders in organ transplant patients. As both these drugs are known to produce renal toxicity, the concomitant use of CSA and Li may be potentially harmful. The present study was undertaken to investigate the effect of CSA and Li chloride individually and in combination on renal structure and function of rats. Male Sprague-Dawley rats were divided into the following eight groups of seven animals each: group I, control (vehicle only); group 2, Li (2 mEq/ kg i.p.) alone; group 3, CSA 12.5 mg/kg (subcutaneous); group 4, CSA 25 mg/kg; group 5, CSA 50 mg/kg; group 6, CSA 12.5 mg/kg + Li; group 7, CSA 25 mg/kg + Li; and group 8, CSA 50 mg/kg + Li. The drugs were given once a day for seven days; Li being administered 30 min before CSA. Twenty four hours after the last dose of drugs the animals were sacrificed and blood samples were analyzed for blood urea nitrogen (BUN), serum creatinine (SCr), CSA and Li levels. The left kidney was analyzed for malondialdehyde (MDA) and conjugated dienes (CD) levels and right kidney was used for histopathological studies. Our results showed that Li alone did not produce any significant renal toxicity, whereas CSA dose dependently caused structural and functional changes in kidneys. However, significantly higher structural and functional impairment was observed in the animals treated with Li plus CSA as compared to CSA alone treated animals. Several fold increase in blood Li level was also noticed in the rats concomitantly treated with CSA and Li. A significant increase in MDA and CD in the rats treated with CSA plus Li suggests the role of oxidative stress in drug induced nephrotoxicity. These findings clearly demonstrate that even non toxic doses of Li may significantly exacerbate CSA induced nephrotoxicity in rats. The enhanced nephrotoxicity following concomitant use of these drugs may be attributed to significant increase in the bioavailability of Li and enhanced oxidative stress. Further clinical studies are warranted to investigate the interaction of these nephrotoxic drugs in human subjects.     

Two-unit cantilevered resin-bonded fixed partial dentures--a retrospective, preliminary clinical investigation

PURPOSE: The aim of this study was to retrospectively evaluate the clinical retention and abutment movement of 2-unit cantilevered resin-bonded fixed partial dentures (FPD) that were inserted at Prince Philip Dental Hospital in Hong Kong. MATERIALS AND METHODS: Of 45 patients who were identified from a hospital computer search after receiving a 2-unit cantilevered resin-bonded FPD, 31 were clinically examined (33 FPDs). For each patient the following data were recorded: gender, age, cementation date, endodontic treatment if performed, bone support, tooth mobility, and FPD tipping or drifting. Data about any debonds with subsequent treatment and patient satisfaction on a 10-point scale were also recorded. RESULTS: The mean service life for the 33 prostheses was 30 +/- 18 months, with a range of 72 days to 67 months. One prosthesis debonded, resulting in a clinical retention rate of 97%. No rotation, drifting, or tipping was observed for any of the prostheses during the short period of this study. CONCLUSION: Two-unit cantilevered resin-bonded FPDs are successful in the short term, but further research is required to determine if they offer a viable alternative to fixed-fixed resin-bonded FPD designs.     

Knowledge and perceptions of diabetes in a semi-urban Omani population

Background  

Diabetes mellitus is a major public health problem in the Sultanate of Oman. This study aimed to evaluate the knowledge and perception of diabetes in a sample of the Omani general population, and the associations between the elements of knowledge and perception, and socio-demographic factors.     

Antinociceptive,anti-inflammatory and antipyretic effects of <Emphasis Type="Italic">Muntingia calabura</Emphasis> aqueous extract in animal models

The present study was carried out to elucidate the potential of aqueous extract of Muntingia calabura leaves aqueous extract (MCAE) as antinociceptive, anti-inflammatory and antipyretic agents using the formalin-, carrageenan-induced paw edema- and brewer’s yeast-induced pyrexia tests in rats. The extract was prepared by soaking the dried powdered leaves of M. calabura in distilled water (dH₂O) overnight. The supernatant obtained, considered as a stock solution (100% concentration/strength), was then diluted to concentrations of 10% and 50% and used together in all experimental models. The MCAE, at concentrations of 10%, 50% and 100%, were found to show significant antinociceptive, anti-inflammatory and antipyretic activities in all tests. However, all of the activities occurred in a concentration-independent manner. The 50% and 100% concentrations of MCAE produced insignificant antinociceptive and antipyretic activities, respectively. Although the 100% concentration of MCAE produced significant (P<0.05) anti-inflammatory activity, the activity was lower than that of the 10% and 50% concentrations of MCAE. Based on the results, we conclude that the M. calabura leaves possessed antinociceptive, anti-inflammatory and antipyretic activities and, thus, justifies the Peruvian folklore claims of its medicinal values.     

Olfactory disorders due to medications: analysis and review of the literature

INTRODUCTION: Olfactory disorders caused by medicinal drug intake are an uncommon occurrence. However, such an etiology should be systematically taken into account and investigated, as olfactory loss may be reversible once the particular treatment has been stopped. CURRENT KNOWLEDGE AND KEY POINTS: An analysis of the literature shows that of the large number of drugs that are apparently responsible for olfactory disorders, this adverse side effect has in fact only been observed in animal study populations, and no clinical case report has been made on the subject. The real toxicity to man is therefore only hypothetical. Of the 150,000 cases recorded in the pharmacovigilance centers in France, only 68 have reported olfactory complications (0.05% of cases), and only 22% of the medical files on this disorder reach a satisfactory level of plausibility. Cardiovascular drugs are mainly implicated in the development of olfactory disorders. Of these, certain drugs in particular should be mentioned: conversion enzyme (ACE) inhibitors which are responsible for taste disorders, some betablockers, and a calcium antagonist (a dihydropyridine derivative). Olfactory disorders have also been reported following administration of drugs used in anesthesia, in cancerology, endocrinology (carbimazole), in immunology (interferon), in the treatment of infectious diseases (ciprofloxacine, dioxycycline, terbinafine), and in rheumatology (D-penicillamine). FUTURE PROSPECTS AND PROJECTS: It is frequently difficult to establish a direct relationship between drug exposure and an olfactory disorder, and it is often not easy to determine with any certainty the causative role of the drug in the development of this disorder.     

Effects of short- and long-term Schwann cell denervation on peripheral nerve regeneration, myelination, and size

Poor functional recovery after peripheral nerve injury has been generally attributed to inability of denervated muscles to accept reinnervation and recover from denervation atrophy. However, deterioration of the Schwann cell environment may play a more vital role. This study was undertaken to evaluate the effects of chronic denervation on the capacity of Schwann cells in the distal nerve stump to support axonal regeneration and to remyelinate regenerated axons. We used a delayed cross-suture anastomosis technique in which the common peroneal (CP) nerve in the rat was denervated for 0-24 weeks before cross-suture of the freshly axotomized tibial (TIB) and chronically denervated CP nerve stumps. Motor neurons were backlabeled with either fluoro-ruby or fluorogold 12 months later, to identify and count TIB motor neurons that regenerated axons into chronically denervated CP nerve stumps. Number, size, and myelination of regenerated sensory and motor axons were determined using light and electron microscopy. We found that short-term denervation of < or =4 weeks did not affect axonal regeneration but more prolonged denervation profoundly reduced the numbers of backlabeled motor neurons and axons in the distal nerve stump. Yet, atrophic Schwann cells retained their capacity to remyelinate regenerated axons. In fact, the axons were larger and well myelinated by long-term chronically denervated Schwann cells. These findings demonstrate a progressive inability of chronically denervated Schwann cells to support axonal regeneration and yet a sustained capacity to remyelinate the axons which do regenerate. Thus, axonal interaction can effectively switch the nonmyelinating phenotype of atrophic Schwann cells back into the myelinating phenotype.     

低温解除阜康阿魏种子休眠和内源激素变化规律的研究

目的研究低温层积解除阜康阿魏种子休眠的规律和解除休眠过程中内源激素量的变化规律。方法种子在4℃低温层积处理,20℃培养箱发芽。高效液相色谱法进行种子内源激素Z、GA3、IAA和ABA的测定。结果低温层积20 d时,种子发芽率为14%,40 d时种子发芽率可达60%以上。解除休眠过程中种子的内源激素量逐渐降低,在低温层积10~20 d过程中GA3与ABA的量比值迅速增大。结论阜康阿魏种子4℃低温层积40 d解除休眠。GA3与ABA的量比是种子休眠的关键因素。IAA和Z对种子萌发的进行有重要影响。