METHODS TO DIAGNOSE AND EVALUATE THERAPY FOR DIABETES

美国糖尿病协会（1998）估计，大约有1600万美国人患有糖尿病。 其中，约有一半的人不知道他们患有这种疾病。 糖尿病神经病变是一种常见的继发性并发症，存在于超过50%的患者中，但只有13%的患者意识到症状。 神经病变的诊断将通过更敏感的非侵入性筛查试验来促进。 这将允许在不可逆变化发生之前更早地开始严格控制血糖。 糖尿病神经病变的远端变性特征表明，感觉受累的最早形态学体征发生在感觉神经的最远段。这些是表皮神经纤维（ENF），它们是C类伤害感受器。 在一些患者中，即使在表皮下神经丛轻度变薄的情况下，ENF也会严重耗尽，仅深50 mum。 我们假设检测到ENFs开始变性将是糖尿病神经病变的最早诊断形态学标志，ENFs再生将是神经病变逆转的第一个标志。 我们将尝试建立新的早期诊断方法，通过定量ENF在皮肤活检和皮肤水疱的无症状的糖尿病患者的短期谁有轻微或无神经病变和无症状的近端皮肤区域的患者与已知的神经病变。最近有几个临床试验用于治疗糖尿病神经病变。 然而，目前的诊断测试不具有评估患者益处所需的灵敏度。我们认为皮肤活检和皮肤水疱方法可以填补这一空白。 我们将首先通过研究两个特定患者组的ENF再生来确定糖尿病受试者再神经支配表皮的能力，其中两个特定患者组的条件有利于再生的发生。 第一种是患有糖尿病神经病变的患者，他们将受到一个小的标准化水泡伤口，该伤口在正常受试者中可以快速愈合和重新神经支配。 第二种是接受功能性胰腺移植的患者，他们随后血糖正常，因此不再是糖尿病患者。最后，本计画将利用皮肤切片及水疱法，以探讨神经生长因子（NGF）是否能促进水疱创面表皮神经纤维的侧支发芽及再生。 在进入糖尿病神经病变临床治疗试验的神经营养因子中，NGF可能最有潜力增强ENF再生，因为其对ENF起源细胞的背根神经节神经元具有特异性。 如果神经生长因子能增强皮肤伤口的神经再支配，这些方法可能有助于评估临床治疗试验的结果。

The American Diabetes Association (1998) estimates that about 16 million Americans have diabetes. Of these, about one-half are unaware that they have the disease. Diabetic neuropathy is a common secondary complication that is present in over 50 percent of patients but only 13 percent are aware of symptoms. Diagnosis of neuropathy would be facilitated by a more sensitive non- invasive screening test. This would allow earlier onset of tight control of blood glucose, before irreversible changes occur. The distal degenerative characteristic of diabetic neuropathy suggests that the earliest morphological signs of sensory involvement occur in the most distal segment of sensory nerves. These are the epidermal nerve fibers (ENFs) which are class C nociceptors. In some patients there is severe depletion of ENFs, even in the presence of mild thinning of the subepidermal plexus, just 50 mum deeper. We hypothesize that detection of beginning degeneration of ENFs will be the earliest diagnostic morphological sign of diabetic neuropathy and that regeneration of ENFs will be the first sign of reversal of neuropathy. We will attempt to establish new methods for early diagnosis by quantifying ENFs in skin biopsies and skin blisters of asymptomatic patients with diabetes of short duration who have minimal or no neuropathy and in non symptomatic proximal skin areas of patients with known neuropathy. Recently there have been several clinical trials for treatment of diabetic neuropathy. However, the current diagnostic tests do not have the sensitivity required to evaluate patient benefit. We believe that the skin biopsy and skin blister methods can fill this void. We will first determine the ability of diabetic subjects to reinnervate epidermis by studying ENF regeneration in two specific patient groups in which conditions are favorable for regeneration to occur. The first are patients with diabetic neuropathy who will be subjected to a small standardized blister wound that is known to heal and reinnervate rapidly in normal subjects. The second are patients who have a functioning pancreas transplant who are subsequently euglycemic and are therefore no longer diabetic. Lastly, this project will use skin biopsy and skin blister methods to determine if nerve growth factor (NGF) can enhance collateral sprouting and regeneration of epidermal nerve fibers in the above blister wound. Of the neurotrophins entered into clinical therapeutic trials for diabetic neuropathy, NGF may have the most potential to enhance ENF regeneration because of its specificity for dorsal root ganglia neurons which are the cells of origin of ENFs. If NGF can enhance reinnervation in the skin wound these methods may be useful to evaluate the results of clinical therapeutic trials.