The origin of the ethylene carbon skeleton in Penicillium digitatum appears to be intimately associated with the Krebs cycle acids, particularly the middle carbon atoms of dicarboxylic acids. Among the other compounds studied, certain carbon atoms of beta-alanine, propionic acid, and methionine can be incorporated into the ethylene carbon skeleton presumably by way of an indirect route via the Krebs cycle acids. Carbon atoms of acrylic acid, particularly C-2, were also found to be incorporated into the ethylene skeleton. Inhibition of ethylene but not respiratory CO(2) formation in the mold by cis-3-chloroacrylic acid at 1 x 10(-3)m pointed to the possibility that acrylic acid may be related to the precursor for ethylene.

Citric Acid Cycle↗

PubMedDate not supplied

Pharmacological characterization of angiotensin II binding sites in the canine pancreas.

High affinity 125I-angiotensin II (Ang II) binding sites were characterized in the canine pancreas. Total binding increased with protein concentration and equilibrium was reached within 60-90 min at 22 degrees C. Specific binding was saturable and averaged 70% of total. Scatchard analysis of binding yielded a KD of 0.48 +/- 0.18 nM with a Bmax of 32.8 +/- 6.5 fmol/mg protein (mean +/- SEM, n = 6). The addition of the reducing agent dithiothreitol increased specific binding two-fold. The rank order of displacement of 125I-Ang II binding by native angiotensin peptides was Ang II greater than or equal to Ang III greater than AngI greater than Ang(1-7) much greater than Ang(1-6). The use of the specific Ang II antagonists CGP 42112A, PD 123177, and DuP 753 revealed that the pancreas expresses two receptor subtypes. The majority of Ang II binding sites in the pancreas could be classified as type 2 (AT2), although type 1 (AT1) sites were also detected. In vitro autoradiography revealed binding sites localized over islet cells, acinar and duct cells, as well as the pancreatic vasculature. In addition, the autoradiographic studies confirmed the predominance of the AT2 receptor subtype throughout the pancreas.

Angiotensin I↗

PubMedDate not supplied

Homocysteine and coronary artery disease.

BACKGROUND: Homocystinuria is a rare autosomal recessive disease complicated by early and aggressive occlusive arterial disease. This may be related to the grossly increased homocysteine concentrations seen in this disease. More recently, milder hyperhomocysteinemia has been proposed as an independent risk factor for coronary artery disease. SUMMARY: Many patients with homozygous homocystinuria develop severe premature atherosclerosis and thromboembolism, probably caused by abnormally high concentrations of homocysteine. Homocysteine undergoes metabolism either by remethylation or transsulfuration, and deficiency or dysfunction of any of the substances that regulate these reactions may lead to hyperhomocysteinemia. Homocysteine may have adverse effects on platelets, clotting factors, and endothelial cells. Studies have demonstrated significantly higher plasma homocysteine levels in patients with occlusive arterial disease than in controls. The causes are not clearly understood but may include deficiency of vitamin B6, vitamin B12, and folic acid and heterozygosity for cystathionine synthase deficiency. Vitamin supplementation can lower plasma homocysteine levels. CONCLUSIONS: Whether measuring plasma homocysteine levels in patients with coronary artery disease should be routine and whether treating hyperhomocysteinemia in these patients may reduce the risk of coronary events remains to be determined.

Coronary Disease↗

PubMedDate not supplied

Homocysteine: update on a new risk factor.

A high fasting plasma homocysteine level is an independent risk factor for atherosclerosis and venous thrombosis. Vitamin therapy can lower homocysteine levels, but no benefit has yet been demonstrated; studies using clinical outcomes as endpoints are now in progress.

Arteriosclerosis↗