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Biomedical subjects

M Kadowaki

Publications and source records attributed to M Kadowaki.

At least 55 records · Page 3Linked to original sources
PubMed1989

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.

Animals↗
PubMed1988

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.

Child↗
PubMed1988

[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.

Arteriosclerosis Obliterans↗
PubMed1987

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.

Amino Acids↗
PubMed1986

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.

Animals↗
PubMed1986

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.

Animals↗
PubMed1985

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.

Amino Acid Sequence↗
PubMed1985

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.

Amino Acids↗