4-Amino-6-methylhept-2-enoic acid: a leucine analogue and potential probe for localizing sites of proteolytic control in the hepatocyte

A recent analysis of leucine analogues has suggested that the carboxyl group is not required for mediating low concentration proteolytic inhibition in liver cells. In designing a probe to localize the regulatory site(s), we tested this hypothesis by synthesizing an analogue with a 2-carbon insert between the carboxyl and alpha-carbon. The Wittig product, a trans olefin, was fully active. Surprisingly, low concentration activity was lost when the double bond was eliminated by hydrogenation although some inhibitory effectiveness at high concentrations was evident. Since the double bond extends the carboxyl group away from the alpha-carbon, the results support the above hypothesis as well as the feasibility of adding functional groups to the carboxyl end of leucine.

Differential regulation of the degradation of myofibrillar and total proteins in skeletal muscle of rats: effects of streptozotocin-induced diabetes, dietary protein and starvation

In order to examine the effects of streptozotocin-induced diabetes, dietary protein, and starvation on protein degradation in skeletal muscle of perfused rat hindquarters, rates of myofibrillar and total protein degradation were estimated from the release of 3-methylhistidine (N tau-methylhistidine, 3-MH) and tyrosine, respectively. In rats fed a 20% protein diet (controls), the fractional degradation rate of myofibrillar protein was approximately 56% of the total muscle protein. In streptozotocin-induced diabetic rats, 3-MH release by perfused muscle increased significantly on d 1 of treatment and sustained a high level thereafter. By contrast, tyrosine release did not change. Feeding a 50% protein diet for 1 wk altered neither 3-MH nor tyrosine release. Protein-free feeding, though, suppressed tyrosine release to 49% of controls, but did not affect 3-MH release. Starvation for 3 d did not affect tyrosine release, but did increase 3-MH release to 203% of controls. These results indicate that in diabetic and starved rats myofibrillar protein is preferentially degraded, while in protein-deficient rats, non-myofibrillar protein degradation is selectively suppressed. From these observations, we conclude that the degradation of myofibrillar and non-myofibrillar proteins in skeletal muscle can be differentially regulated.

A pulsatile pump for cardiopulmonary bypass and its clinical use

A pulsatile pump driven by a coil spring, which was designed and constructed by us, is described in this report. It consists of two main parts, a disposable blood chamber and a driving section. The blood chamber has two leaflet valves and a piston, which is covered with two bellofram rolling diaphragms and moves into the housing to draw in and eject the blood. The driving section consists of three cams, an electric motor and a coil spring. The ejection force is wholly produced by the compressed coil spring and is transmitted to the piston in the blood chamber by a rod. This pump allows the ejection pressure, the beat rates, and the stroke volume all to be changed independently. The performance of the pump was tested by using a circulation model where the beat rate was adjusted from 30 to 250 bpm. The output subsequently increased from 0.8 l/min to 5.7 l/min and the stroke volume, from 20.4 ml to 36.7 ml. This new pump has been used for clinical cardiopulmonary bypasses in 24 patients of open heart surgery and the pressure traces during perfusion resembled those of the patients' own hearts.

[Late occlusion at the anastomosis site of an extended polytetrafluoroethylene (E-PTFE) graft with small caliber]

Recently expanded polytetrafluoroethylene (E-PTFE) graft is often used in arterial bypass for atherosclerosis obliterans. In our series of 38 patients (48 legs) undergoing femoropopliteal bypass with E-PTFE graft of 6mm-caliber, a cumulative patency rate was 40.8% at 36 months after operation and a mean duration of patency was 26.3 months. To clarify the cause of occlusion, the diseased grafts were removed and histopathologically examined. Macroscopically, the E-PTFE graft was occluded by the intimal hyperplasia, so called pannus ingrowth from the recipient artery into the graft. The pannus formation of the graft was more remarkable in the distal than in the proximal site of anastomosis, suggesting the influence of blood flow on its formation. Microscopically, no endothelial cells were observed inside the E-PTFE graft except for the surface of pannus. Thus, less extension of endothelialization was thought to be a cause of late occlusion in E-PTFE grafts. Most desirable is the autologous saphenous vein for femoropopliteal bypass. However, when it is not available, E-PTFE graft with a larger caliber must be used in combination with postoperative anticoagulant therapy.

Multiphasic control of hepatic protein degradation by regulatory amino acids. General features and hormonal modulation

Previous studies with livers from fed rats perfused in the single-pass mode have shown that regulatory amino acids (Leu, Tyr, Gln, Pro, Met, His, and Trp) as a group as well as leucine alone inhibit deprivation-induced protein degradation optimally at 0.5 and 4 times (X) normal plasma amino acid concentrations. However, they lose inhibitory effectiveness almost completely within a narrow zone centered at normal (1 X) levels (Pösö, A. R., Wert, J. J., Jr., and Mortimore, G.E. (1982) J. Biol. Chem. 257, 12114-12120; Pösö, A. R., and Mortimore, G. E. (1984) Proc. Natl. Acad. Sci. U. S. A. 81, 4270-4274). We now report similar effects for tyrosine and glutamine and suggest that this multiphasic dose response is a general feature of the regulatory group. Insulin (2.4 micrograms h-1) selectively modulated the response by abolishing the zonal loss, whereas glucagon (10 micrograms h-1) blocked the initial inhibition (0.5 X); proteolytic suppression was restored at 4 X normal plasma levels. Although the zonal loss of inhibition at 1 X was associated with a near maximal increase in the volume density of macroautophagy, the vacuoles differed from those induced by stringent amino acid deprivation in containing 4.5-fold more smooth than rough endoplasmic reticulum and thus represented a separate population. Surprisingly, the leucine analog, L-alpha-hydroxyisocaproate, elicited multiphasic responses identical to those of L-leucine, including inhibition at 0.1 mM (equivalent to 0.5 X Leu). Inasmuch as alpha-ketoisocaproate is not effective at this concentration, the initial suppression of protein degradation could be mediated from a site that recognizes structural features common to leucine and its hydroxyl analog.

The effect of microbial contamination on musculocutaneous and random flaps

Although musculocutaneous flaps have been shown to have the ability to withstand a greater inoculum of bacteria than random flaps, it has not been shown that the musculocutaneous flap has any greater ability to decrease the bacterial population in a contaminated wound. In this series of experiments, granulating wounds were developed containing 10(4), 10(5), or 10(6) bacteria per gram of tissue. These contaminated wounds were then covered either with musculocutaneous flaps, random flaps, or left uncovered as a control. In the heavily contaminated wounds containing 10(6) bacteria per gram of tissue, neither type of flap was able to prevent bacterial proliferation and all flaps dehisced. In the minimally contaminated wounds containing 10(4) bacteria per gram of tissue, both the musculocutaneous and random flaps achieved wound healing and decreased the bacterial level in the wound. However, in the intermediate group containing 10(5) bacteria per gram of tissue, musculocutaneous flaps lowered the bacterial count and allowed wound closure, whereas the random flaps did not control the bacterial growth and failed. Therefore, in the moderately contaminated wound, musculocutaneous flaps are advantageous and can decrease bacterial counts and obtain successful closure when random flaps cannot.

Helodermin has a VIP-like effect upon canine blood flow

The effect of helodermin on vascular physiology was studied in anesthetized dogs using a synthetic replicate of helodermin and helodermin related peptides. Intraarterial infusion of helodermin caused a dose-dependent increase in femoral blood flow. Helodermin was 16 times less potent than VIP and 5 times more potent than PHM (human PHI). The helodermin effect lasted significantly longer; the half-life of the helodermin effect was 6.5 times longer than VIP. Synthetic helodermin (Hd) N-terminal fragment Hd(1-27)NH2 retained substantial activity similar to the full helodermin molecule but the prolonged effect was lost. Hd(7-35) and Hd(22-35) were inactive in this system. Intravenous injection of synthetic helodermin produced prolonged systemic hypotension and tachycardia; and, similar to VIP, it increased the common carotid arterial blood flow while those of the superior mesenteric and femoral arteries were decreased. The results demonstrate the VIP-like vasodilating activity and cardiovascular effects of helodermin in anesthetized dogs.

Rat pancreas contains the proglucagon(64-69) fragment and arginine stimulates its release

Rat proglucagon(64-69) corresponding to the C-terminal hexapeptide of putative rat glicentin sequence in the precursor was synthesized. A glicentin C-terminal hexapeptide specific radioimmunoassay, using the synthetic hexapeptide as standard, demonstrated the presence in rat pancreas of a peptide identified with the synthetic rat proglucagon(64-69): H-Asn-Arg-Asn-Asn-Ile-Ala-OH. The hexapeptide was released concomitantly with glucagon by arginine stimulation from the isolated perfused rat pancreas. The results indicate that the pancreas co-stores and possibly co-releases the hexapeptide with glucagon as one of the processing products of proglucagon.

Effects of insulin, amino acids and fasting on myofibrillar protein degradation in perfused hindquarters of rats

The rate of 3-methylhistidine (3-MH) release from rat perfused hindquarters was measured to investigate the effects of insulin, amino acids and fasting on myofibrillar protein degradation. Since release of 3-MH into the perfusate increased linearly and the pool of free 3-MH in the perfused muscle did not change significantly during 2 h of perfusion, it was concluded that 3-MH release reflected the rate of myofibrillar protein degradation. Tyrosine release in the presence of cycloheximide represented the degradation rate of total muscle protein. Insulin suppressed the net release of tyrosine in normal rats, but did not affect the rate of release of 3-MH and tyrosine in the presence of cycloheximide. 3-MH release was not influenced by perfusate amino acid concentrations at zero to 5 times the normal plasma levels. When rats were fasted for one and two days, 3-MH release increased 1.7 and 2.6 times, respectively, compared with the fed rats, which showed that the rate of degradation of myofibrillar protein in skeletal muscle rose just after the beginning of fasting.

Regulation of plasma amino acid levels by perfusion of hindquarters of rats

To clarify the role of skeletal muscle in the regulation of plasma amino acid levels, we investigated the response of skeletal muscle to changes in plasma amino acid levels using the perfusion technique of rat hindquarters. The hindquarters of overnight-fasted rats were perfused with a medium containing no amino acids (0 X) and amino acids with plasma levels simulating normal (1 X) or 5 times the normal levels (5 X). Each amino acid level in the perfusate changed in various ways during a 2 h perfusion. The characteristics of amino acid flows in response to the changes in their perfusate levels were divided into four groups as follows: the amino acids which are always taken up irrespective of their plasma levels: glutamate and aspartate; those which are always released: alanine, glutamine and glycine; those which are taken up or released depending on their plasma levels: valine, leucine, isoleucine, serine and (threonine); and those which are released at lower, but neither taken up nor released, at higher plasma levels: tyrosine, phenylalanine, tryptophan, histidine, methionine, asparagine, arginine, lysine and proline. Comparing these results with the data of liver perfusion (Bloxam, D.L. (1971): Br. J. Nutr., 26, 393-422), we assumed that skeletal muscle plays a role complementary to liver in the regulation of plasma amino acid levels.

Effects of sodium ursodeoxycholate, hyodeoxycholate and dehydrocholate on cholesterol and bile acid metabolism in rats

Effects of sodium ursodeoxycholate, hyodeoxycholate and dehydrocholate on serum and liver cholesterol levels, bile flow, biliary cholesterol, phospholipid and bile acid secretions, and fecal sterol and bile acid excretions were examined with Wistar strain male rats fed ordinary and 2% cholesterol supplemented diets. Dehydrocholate increased the liver cholesterol level, bile flow and biliary lipid secretion, but ursodeoxycholate and hyodeoxycholate did not. The serum cholesterol level was not changed by the treatments. Ursodeoxycholate and hyodeoxycholate increased their own secretion into the bile and decreased cholic acid secretion, while dehydrocholate increased deoxycholic acid and oxo bile acid secretion. Ursodeoxycholate increased but dehydrocholate decreased the fecal sterol excretion, and hyodeoxycholate caused no change. Dehydrocholate decreased the fecal coprostanol level. The total amounts of the fecal bile acids were similar in all the treated groups, but ursodeoxycholate increased lithocholic acid, alpha, beta- and omega-muricholic acids and ursodeoxycholic acid; hyodeoxycholate increased hyodeoxycholic acid, 3 alpha, 7 beta, 12 alpha-trihydroxy-5 beta-cholanoic acid and oxo bile acids; and dehydrocholate increased deoxycholic acid, cholic acid, omega-muricholic acid and oxo bile acids and decreased hyodeoxycholic acid. These data suggested that ursodeoxycholate was transformed into lithocholic and muricholic acids, and dehydrocholate into cholic and deoxycholic acids during the enterohepatic circulation, but hyodeoxycholate showed almost no change. Ursodeoxycholate and hyodeoxycholate caused neither accumulation of cholesterol in tissues nor increase in bile flow and biliary lipid secretion as well as chenodeoxycholate did. The biological effect of dehydrocholate was similar to that of cholate, and this was partially due to its conversion into cholic acid and deoxycholic acid.

Effect of bile duct ligation on bile acid metabolism in rats

The effect of bile duct ligation on the quantitative and qualitative changes of bile acids in serum, liver, urine, and feces, and the concentration of cholesterol and phospholipids in serum and liver were examined in male rats. The concentration of bile acids in serum increased over 100-fold on day 5 but was lower than the 5-day level on days 10 and 15. The concentration in the liver also increased about 10-fold. beta-Muricholic acid predominantly increased but the secondary bile acids, deoxycholic acid and hyodeoxycholic acid, decreased. The urinary excretion of bile acids increased to about 40 mg/day per rat on the first day of bile duct ligation but this increase was reduced on day 2 to about half and remained at that level until day 24. These values exceeded that of fecal bile acids, 12 mg/day per rat, before bile duct ligation. The amount of bile acid sulfates in the urine was as low as 1% of the total. The urinary non-sulfated bile acids consisted mainly of beta-muricholic acid (60%) and cholic acid (20%), while the sulfates contained a considerable amount of unidentified acidic substances (40%) in addition to cholic acid and beta-muricholic acid. The concentration of cholesterol and phospholipids in serum markedly increased on day 5 but declined gradually thereafter. The liver cholesterol concentration did not change but the phospholipid concentration decreased. Fecal sterols did not change in both the total amount and composition. These data indicated that daily synthesis of bile acids, especially beta-muricholic acid, was accelerated in bile duct-ligated rats.

Altered bile acid metabolism in alloxan diabetic rats

Changes of cholesterol, phospholipid, triglyceride or bile acid levels in serum liver, bile and feces after the treatment with alloxan were examined in Wistar strain male rats. Serum cholesterol, phospholipid and triglyceride levels and liver cholesterol level markedly increased but liver phospholipid and triglyceride levels remained unchanged. The lipid levels in serum very low density and low density lipoproteins were elevated but those in high density lipoprotein were not. Bile flow was not changed but biliary secretion of cholesterol, phospholipid and bile acids markedly increased. Among the biliary bile acid components, cholic acid markedly increased but the amount of chenodeoxycholic acid was similar to that of normal rats. Fecal excretion of deoxycholic acid increased but that of lithocholic and hyodeoxycholic acids decreased, and alpha, beta- and omega-muricholic acids did not change, thus, the total amount of fecal bile acids remained unchanged. Hepatic cholesterol synthesis was markedly depressed, while cholesterol 7 alpha-hydroxylase activity did not change and cytochrome P-450 content was elevated by about 40%. From such evidence, it was apparent that synthesis of cholic acid increased while that of chenodeoxycholic acid decreased and the total amount of bile acids synthesized did not change in the diabetic rats. Furthermore, marked increase of the pool size of cholic acid and hepatic secretion of cholic acid stimulated the absorption of lipids and produced a hyperlipidemia in the diabetic rats.

Age-related changes in cholesterol and bile acid metabolism in rats

Age-related changes in serum and liver cholesterol, phospholipid and triglyceride levels, serum lipoproteins, biliary secretion of cholesterol, phospholipid and bile acids, and fecal excretion of sterols and bile acids were examined in Sprague-Dawley and Wistar strain male rats, 7 to 106 weeks in age. Serum and liver lipid levels increased with age in both strains but the liver phospholipid level remained unchanged. The proportion of serum alpha-lipoprotein increases and that of beta- and prebeta-lipoproteins slightly decreased. Cholesterol and phospholipids in low density lipoprotein and cholesterol in high density lipoprotein fractions also increased with age. Bile flow and biliary secretion of cholesterol and bile acids decreased in aged rats, but when they were expressed in terms of units per rat they were almost constant without regard to age. Pool size, synthesis, secretion, and turnover frequency of bile acids also did not change when they were expressed per rat, though 7-week-old rats showed a low value for turnover frequency. Biliary secretion of phospholipid, however, increased in aged rats. Biliary secretion of chenodeoxycholic and alpha-muricholic acids decreased but that of cholic and hyodeoxycholic acids increased. Daily excretion of feces and fecal neutral sterols decreases in aged rats but the excretion of bile acids remained constant regardless of age. The ratio of coprostanol and cholesterol in the total sterols was not affected. Fecal lithocholic, beta-muricholic and P10 (probably omega-muricholic) acids were decreased with age but the other bile acid components were not changed or were slightly increased.

Dextran derivatives in single and combination chemotherapy against transplantable mouse ascites and solid tumors

Dextran, a typical homopolysaccharide without antitumor activity, was modified by palmitoylation and/or phosphorylation to yield three derivatives: palmitoyldextran phosphate, dextran phosphate, and palmitoyldextran. Of these compounds, only palmitoyldextran phosphate showed growth-inhibitory activity against Ehrlich solid tumor in mice. In combination therapy with mitomycin C, bleomycin, cyclophosphamide, and 5-fluorouracil, palmitoyldextran phosphate manifested strong synergistic effects against both Sarcoma 180 ascites and L1210 leukemic tumors. The compound is not directly cytocidal against Sarcoma 180 ascites tumor, but it appears to act via activation of peritoneal macrophage. The antitumor activity of palmitoyldextran phosphate apparently is mainly due to immunological host-mediated mechanisms.

Effects of synthetic progestational steroids on liver and serum lipids in rats

Effects of norethisterone (NT) purified norethisterone (pure NT), norethynodrel (NE), medroxyprogesterone acetate (MAP), chlormadinone acetate (CMA) and desoxycorticosterone acetate (DOCA) on serum and liver lipid levels and serum lipoproteins were examined in both intact and estradiol-treated male rats. NT and NE caused a decrease in serum cholesterol and phospholipid levels, an increase in liver cholesterol level, no significant change in triglyceride levels of both serum and liver, with a significant change in serum lipoprotein patterns; a decreased in alpha- and beta-lipoproteins and a marked increase in pre beta-lipoprotein. Pure NT decreased serum cholesterol without causing any change in lipoprotein pattern. MAP, CMA and DOCA causee almost no effect on lipid levels in serum and liver, but CMA and DOCA increased alpha-lipoprotein and decreased beta- and pre beta-lipoproteins. An acute treatment with estradiol caused a decrease in alpha- and beta-lipoproteins and an increase in pre beta-lipoprotein with a decrease in serum lipid levels and an increase in liver lipids. By contrary, a chronic treatment with a marked hypercholesterolemia. This increase of alpha-lipoprotein in estradiol-treated rats was prevented by NT and NE, not affected or rather decreased by MAP but further increased with CMA and DOCA. These data suggest that the effects of synthetic progestational steroids on lipids are classified into two groups, 19-nortestosterone derivatives and 17alpha-hydroxyprogesterone derivatives including DOCA. The former caused a decrease in serum lipid levels with an increase of pre beta-lipoprotein and adecrease of alpha-lipoprotein. The latter caused almost no change or a slight increase in serum lipid levels with a decrease in pre beta-lipoprotein and an increase in alpha-lipoprotein, though it was not found in MAP.