Bioavailability of methionine in some tripeptides occurring in dietary proteins as determined by rat growth

Relative bioavailability of methionine (L-Met=100) in tripeptides found in β-casein (Ala-Met-Ala; Ala-D-Met-Ala; Val-Met-Phe; Val-D-Met-Phe) and in soy glycine (Thr-Met-Arg; Thr-D-Met-Arg; Thr-Met-Lys) was determined by the rat growth method using net protein ratio (NPR) as the performance index. Crystalline D-Met was completely available to the growing rat, but in the tripeptide form, D-Met (0–45%) was considerably less available than L-Met (38–71%). The bioavailability of Met was also influenced by the side chain of the adjacent amino acids. Met in the tripeptides with the bulky amino acids (Val-Met-Phe, Thr-Met-Arg, Thr-Met-Lys) was less available than in the unhindered tripeptide (Ala-Met-Ala). D-Met in the hindered tripeptides (Val-D-Met-Phe, Thr-D-Met-Arg) did not support rat growth at all.     

Tumorous aneurysms

Summary Intracranial aneurysms commonly present with subarachnoid hemorrhage. Rarely, they may attain a large size and manifest exclusively as intracranial space-taking lesions. We have collected a series of 48 cases of large aneurysms; 47 of them have been previously unpublished. To our knowledge, this is the largest series on this subject.This work was supported in part by a Special Fellowship Award from the National Institute of Neurological Diseases and Stroke #1F11NS2677 NSRB (Dr. Sarwar); #2F11NS2576 NSRB (Dr. Batnitzky) and a Neuroradiology Training Program Grant #NSO 5290 (Dr. Schechter).     

Computed tomography of temporal bone pneumatization: 2. Petrosquamosal suture and septum

The degree of visualization of the petrosquamosal (K?rner's) septum on high-resolution axial computed tomography (CT) in 141 temporal bones (100 subjects) was analyzed. The superior and inferior parts of the septum were assessed separately and were seen in 75% and 41% of cases, respectively. There was no relation between the size of K?rner's septum and pneumatization. The clinical relevance of this finding is discussed. The CT features of the ventral petrosquamosal suture also were investigated. The crista tegmentalis, a contribution of the petrosal tegmen to the mandibular fossa, was seen on CT as a polypoid excrescence projecting from the ventrolateral petrous pyramid. This knowledge is useful in the radiographic analysis of the course of longitudinal fractures of the petrous bone.     

Campylobacter pylori infection in patients undergoing endoscopy in Fiji

Forty two patients (20 Fijian and 22 Indian) presenting for endoscopy at the Colonial War Memorial Hospital, Suva, Fiji, were biopsied to detect Campylobacter pylori infection. Detection of the organism's urease activity in biopsy material or seeing the organism in Warthin-Starry silver stained histology sections were used to diagnose infection. Thirty-nine patients (93%) were infected; 19 of 20 Fijians (95%) and 20 of 22 Indians (91%). Of the 39 infected patients, 37 (95%) had chronic active gastritis and 24 (62%) had active peptic ulcer disease. The implications of these findings in relation to the management of endoscopy patients in Fiji are discussed.     

Differences in uricogenic effects of dietary purine bases, nucleosides and nucleotides in rats

The uricogenic effects of dietary free purines (adenine, guanine, hypoxanthine and xanthine), their nucleosides (adenosine, monophosphate, guanosine monophosphate and inosine monophosphate) were studied in rats. Casein-based diets (20% protein) supplemented with 30 mmol/kg diet of each of the free purine base, nucleoside or nucleotide were fed to male Sprague-Dawley rats (100 +/- 5 g) for 14 d. Addition of adenine resulted in less weight gain than in controls, greater kidney weight, greater urine volume and higher levels of blood urea nitrogen, serum uric acid, creatinine and allantoin but lower urinary levels of allantoin, uric acid and creatinine. The adenine diet also caused nephropathy characterized by nephromegaly and deposition of crystals. A microscopic examination of the kidneys revealed deposition of crystals mainly in the lumen of convoluted tubules of the cortex. Feeding of diets containing other purine bases, nucleosides and nucleotides had no adverse effects on kidney weight or structure, urine volume, serum uric acid or creatinine. Urinary allantoin excretion, however, was greater in rats fed hypoxanthine, xanthine, nucleoside and nucleotide diets than in control rats. Adenine produced adverse effects only when fed in the free form and not when fed as the nucleoside or nucleotide, suggesting a metabolic significance for free adenine in predicting hyperuricemic effects of foods.     

Uricogenic potential of selected cooked foods in rats

Samples of beefsteak, beef liver, haddock, and mushrooms were cooked by two methods: boiling and broiling. Growth and purine metabolism in rats fed diets containing 20% protein (N x 6.25) were studied for a period of 26 days. The cooked meats and fish were used as the sole source of dietary protein, while cooked mushrooms provided 5% protein in mushroom-casein diets. Body weight, and food and water intakes were recorded weekly while total urine was collected during the last 6 days of the feeding period. Levels of purine metabolites (uric acid and allantoin) in blood and urine were determined by enzymatic methods and reverse-phase HPLC techniques. Dietary treatments had no significant effects on weight gain and food consumption. Compared with animals fed the casein control diet, rats fed the broiled liver, broiled haddock, and boiled mushroom diets had significantly (p less than 0.05) higher concentrations of serum allantoin, suggesting that uricogenicity of these foods was influenced by the method of cooking. The renal excretion of purine metabolites was significantly correlated with purine intake, the renal excretion of allantoin and uric acid being the highest in rats fed the liver diets.     

Ticrynafen and hydrochlorothiazide in hypertension.

In a double-blind study, 28 patients having mild to moderate essential hypertension were randomly assigned to a 6-week regimen of ticrynafen, hydrochlorothiazide, or placebo. Blood pressure fell after ticrynafen and hydrochlorothiazide. Serum uric acid fell strikingly with ticrynafen whereas it rose with hydrochlorothiazide. Serum potassium declined very little with ticrynafen; much less than with hydrochlorothiazide. Serum creatinine and blood urea nitrogen rose slightly more with ticrynafen than with hydrochlorothiazide. There were no clinical adverse effects to either of the medications. Ticrynafen appears to be an effective antihypertensive with a substantial hypouricemic effect.     

Effects of supplemental cystine or methionine on growth and lifespan of stroke-prone spontaneously hypertensive rats

Stroke-prone spontaneously hypertensive (SHRSP) rats are considered a suitable model for studying the effects of dietary and other environmental factors on human essential hypertension and haemorrhagic stroke. To investigate the suitability of a control diet for this strain of rats, we studied the effects of supplementing casein and soya protein isolate (SPI) with two sulphur amino acids (methionine and cystine) on the growth and lifespan of SHRSP rats. The source of dietary protein and the type of supplemental sulphur amino acid had significant (P < 0.05) effects on food intake and weight gain measured after 31 d of the feeding study, while only the type of supplemental sulphur amino acid had significant effects on mean survival times and the survival rates. On average, the casein groups had higher food intake and weight gain compared with the SPI groups. The methionine-supplemented groups had lower food intake but higher weight gain than the cystine-supplemented groups. Similarly, the methionine-supplemented groups had higher mean survival times and survival rates compared with the cystine-supplemented groups. The data would suggest that a control diet based on cystine-supplemented casein (as recommended for normal healthy rats by the American Institute of Nutrition), may not meet the sulphur amino acid requirements for SHRSP rats, and that the methionine-supplemented casein would be an appropriate control diet for this animal model.