Glutamine-dependent carbamoyl-phosphate synthetase was purified about 2100-fold from the cytosol of rat liver using 30% (v/v) dimethyl sulfoxide and 5% (w/v) glycerol as stabilizers. Throughout the purification, aspartate transcarbamylase and dihydroorotase, the second and third enzymes of pyrimidine biosynthesis, were copurified with the synthetase. These three enzymes sedimented as a single peak with a sedimentation coefficient of 27 S in sucrose gradients containing the stabilizers, indicating their existence as a multienzyme complex. The aggregation states of the complex were analyzed by sucrose gradient centrifugation under conditions approximating those used for enzymatic assay and correlated with the kinetic properties of the synthetase. In the presence of 10% glycerol and 10 mM MgATP(2-) at 18 degrees, the synthetase showed high activity and the three enzymes sedimented as a single peak with a coefficient of 25 S. The three enzymes also existed as a complex with the same coefficient when 50 muM PP-ribose-P was added in place of MgATP(2-), the sedimentation coefficient of the complex shifted to 28 S, indicating alteration in its molecular shape, rather than size. With 10% glycerol alone, the complex partially dissociated and the synthetase activity appeared in three peaks with coefficients of 26, 19, and 9 S (carbamoyl-phosphate synthetases (CPSase) a, b, and c, respectively). CPSases a, b, and c, thus obtained, were all sensitive to regulation by UTP and PP-ribose-P, but they differed MgATP(2-) (5.1, 4.8, AND 1.7 mM for CPSases a and b, and the enzyme within the original complex, respectively) and in their sensitivities to effectors. These results suggest that the aggregation may modify the catalytic and regulatory properties of the synthetase; Attempts to reassociate the components were unsuccessful.

In perifused pancreatic islets, the fluorescence of oxidized flavoproteins (FAD) was recorded continuously. Elevation of glucose concentration in the medium form 0 or 5 mM to 20 mM led to decrease in FAD-fluorescence beginning 10 sec after change of medium. L-leucine (10 mM), (+/-)-B-BCH (20 mM) and alpha-ketoisocaproic acid (10 mM) caused typical kinetics of FAD-fluorescence decrease. The results are interpreted to indicate rapid changes of the functional state of B-cell mitochondria induced by the above-mentioned stimulators of insulin release.

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Six Japanese cases of griseofulvin (GF)‐induced photodermatitis were reported. All of the patients had received GF from 4 days to 4 months as treatment for tinea unguium. Clinical features were basically eczematous, but differed somewhat case by case. Patient 2 showed pigmentation and depigmentation and patient 5 showed pellagra‐like eruptions. From the clinical view, we could not differentiate precisely between phototoxic and photoallergic reactions. The difference may also depend on response severity, duration of skin eruption, or skin color. Blood and urine porphyrins were within normal ranges. An action spectrum study revealed that UVA was responsible for eliciting a photosensitivity reaction. Patch and photopatch tests were performed on all 6 patients. The results of the photopatch tests were positive for 3 patients and negative for the other 3. The degrees of reaction to photopatch tests differed so widely that it was difficult to determine suitable conditions for UVA intensity or GF concentrations for photopatch testing. Moreover, half of the patients showed negative photopatch tests. Although there is merit in the use of photopatch tests for studying the causes of systemically administered drug‐induced photodermatitis, there may also be limits to their usage. When performed carefully, drug readministration is a more reliable method. From the results of positive photopatch tests, photocross reactions between GF and penicillin, persistent light reactions and distant flare up phenomena, we concluded that in some of our cases, reactions were photoallergic. Histological findings showed non‐specific inflammatory changes. Direct immunofluorescence studies showed that immunoglobulin and complement were deposited at papillary perivascular areas and the dermo‐epidermal junction.