Clinical characteristics, and time course of pancreatic beta-cell function and glutamic acid decarboxylase antibodies in Thai patients with adult-onset Type 1 diabetes: distinction between patients of rapid- and slow-onset.

In order to study the clinical characteristics, time course of beta cell function and glutamic acid decarboxylase antibodies (GAD65Ab) in Thai patients with adult-onset Type 1 diabetes and to examine the distinctive features between patients with rapid-and slow-onset, 61 Thai patients with Type 1 diabetes who had age of disease onset at or after 20 years were studied. All patients were treated with insulin at the time of study and had fasting C-peptide levels +/-0.33 nmol/l. Twenty-six (42.6%) were in rapid-onset and 35 (57.4%) were in slow-onset groups. Fourty-four of 61 (70.5%) were male. About three-fourths had body mass index (BMI) < 19 kg/m2 at the time of insulin therapy. Only 7 of 61 (11.5%) patients had ketoacidosis at first presentation. Five patients had associated autoimmune thyroid disease and 10 (16.7%) patients had family history of diabetes in first-degree relatives. GAD65Ab was positive in 31 patients (50.8%); 10 (38.5%) were in rapid-onset and 21 (60.0%) were in slow-onset groups. GAD65Ab particularly of high levels were persistently elevated during 3-4 years follow-up period. The persistence of GAD65Ab were not associated with changes in fasting C-peptide levels. At the time of insulin dependency, there were no distinctive clinical features between rapid- and slow-onset patients except higher fasting C-peptide (0.08+/-0.08 vs. 0.14+/-0.10 nmol/l; p = 0.023) and GAD65Ab levels (19.6+/-17.4 vs. 46.1+/-49.7 U/ml; p = 0.036) in slow-onset patients. Fasting C-peptide levels of patients in the latter group were also demonstrated to be higher after 3-4 years of follow-up. In conclusion, most Thai patients with adult-onset Type 1 diabetes in this study were male and had significant degree of weight loss and lean BMI prior to insulin therapy. The presence of GAD65Ab did not predict clinical features or rate of beta cell loss. Patients in rapid-onset group had lower fasting C-peptide and GAD65Ab levels than those of slow-onset group which confirms the slower process of beta cell failure in the latter.     

The elicitin secreted by Phytophthora palmivora, a rubber tree pathogen

Palmivorein, a new member of the elicitin family, was purified from the culture filtrate of Phytophthora palmivora isolated from the rubber tree, Hevea brasiliensis. The elicitin was obtained by ammonium sulfate precipitation and further purified using ion-exchange and gel filtration. The molecular weight, isoelectric point, amino acid composition and N-terminal sequences of this molecule are reported and compared to other known elicitins. Palmivorein, as determined by SDS-PAGE, is a small protein of M(r) ca. 10,000. It is classified as an alpha-elicitin according to its acidic pI and the valine residue at position 13. Like other elicitins, the P. palmivora elicitin causes tissue necrosis on tested tobacco leaves. It also causes severe wilting and necrosis of Hevea tissue, and leaves of the susceptible rubber clone (with respect to P. palmivora) are much more sensitive to this elicitin than those that are resistant.     

Biosynthesis of scopoletin in Hevea brasiliensis leaves inoculated with Phytophthora palmivora

Inoculation of resistant (R) and susceptible (S) Hevea brasiliensisleaves with Phytophthora palmivorainduced foliar necrosis and biosynthesis of scopoletin (Scp), considered as a Heveaphytoalexin. The degree of resistance of four clones, as classified by the necrotic lesions, was related to the rapidity and intensity of Scp production. The resistant BPM-24, and marked partially resistant clone PB-235, displayed an early secretion of scopoletin that intensified and lasted longer than the weak partially resistant RRIT251, and susceptible clone RRIM600. The lesion size and amount of Scp after infection were positively correlated to the concentration of spores applied to Hevealeaves. In addition, in leaflets inoculated with high spore concentration, Scp reached the highest level earlier than those with low spore concentration. A fungitoxic effect of Scp on mycelium growth was shown in bioassays; the I₅₀ value tested on Phytophthora palmivora was relatively the same as on Phytophthora botryosa, but much lower than those found on other leaf pathogens of rubber tree, Corynespora cassiicolaand Colletotrichum gloeosporioides. The lesion size and level of Scp upon spore inoculation may be appropriate for classifying Heveaclones according to their R/S with respect to P. palmivora