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Biomedical subjects

C Sumi

Publications and source records attributed to C Sumi.

At least 19 recordsLinked to original sources
PubMed2000

An effective ultrasonic strain measurement-based shear modulus reconstruction technique for superficial tissues--demonstration on in vitro pork ribs and in vivo human breast tissues.

An effective shear modulus reconstruction technique is described which uses ultrasonic strain measurements for diagnosis of superficial tissues, i.e. our previously developed ultrasonic strain measurement and shear modulus reconstruction methods are combined and enhanced. The technique realizes very low computational load, yet yields fairly high quantitativeness, high stability and spatial resolution, and large dynamic range. The suitability of the method is demonstrated on in vitro pork ribs and in vivo human breast tissues (fibroadenoma and scirrhous carcinoma).

Adenocarcinoma, Scirrhous↗
PubMed1998

A robust numerical solution to reconstruct a globally relative shear modulus distribution from strain measurements.

To noninvasively quantify tissue elasticity for differentiating malignancy of soft tissue, we previously proposed a two-dimensional (2-D) mechanical inverse problem in which simultaneous partial differential equations (PDE's) represented the target distribution globally of relative shear moduli with respect to reference shear moduli such that the relative values could be determined from strain distributions obtained by conventional ultrasound (US) or nuclear magnetic resonance (NMR) imaging-based analysis. Here, we further consider the analytic solution in the region of interest, subsequently demonstrating that the problem is inevitably ill-conditioned in real-world applications, i.e., noise in measurement data and improper configurations of mechanical sources/reference regions make it impossible to guarantee the existence of a stable and unique target global distribution. Next, based on clarification of the inherent problematic conditions, we describe a newly developed numerical-based implicit-integration approach that novelly incorporates a computationally efficient regularization method designed to solve this differential inverse problem using just low-pass filtered spectra derived from strain measurements. To evaluate method effectiveness, reconstructions of the global distribution are carried out using intentionally created ill-conditioned models. The resultant reconstructions indicate the robust solution is highly suitable, while also showing it has high potential to be applied in the development of an effective yet versatile diagnostic tool for quantifying the distribution of elasticity in various soft tissues.

Biomechanical Phenomena↗
PubMed1997

[Aprotinin 2 million KIU reduces perioperative blood loss in patients undergoing primary total hip replacement].

We investigated consecutive patients undergoing primary total hip replacement surgery who were randomly assigned into two groups; those who received a blinded solution of aprotinin 2 million KIU (kallikrein inactivation units) (n = 11) and those who received an equivalent volume of normal saline placebo (n = 10) throughout the surgical procedure. Anesthesia and surgical techniques were standardized. All patients received spinal anesthesia combined with general anesthesia. There was no significant difference in blood loss during operation between the two groups. However, postoperative blood loss in the aprotinin group (284 +/- 155g, mean +/- SD) was significantly less compared with that in the control group (723 +/- 334g). Total blood loss in the aprotinin group (820 +/- 255g) was also significantly less than in control group (1265 +/- 389g). We conclude that the use of aprotinin 2 million KIU during total hip replacement results in significantly less perioperative blood loss, especially during the postoperative period.

Aged↗
PubMed1995

Estimation of shear modulus distribution in soft tissue from strain distribution.

In order to obtain noninvasively quantitative static mechanical properties of living tissue, we propose a new type of inverse problem by which the spatial distribution of the relative elastic modulus of the tissue can be estimated only from the deformation or strain measurement. The living tissue is modeled as a linear isotropic incompressible elastic medium which has the spatial distribution of the shear modulus, and the deformation or strain is supposedly measured ultrasonically. Assuming that there is no mechanical source in the region of interest, we derive a set of linear equations in which unknowns are the spatial derivatives of the relative shear modulus, and the coefficients are the strain and its spatial derivatives. By solving these equations, the spatial derivatives of the relative shear modulus are determined throughout the region, from which the spatial distribution of the relative shear modulus is obtained by spatial integration. The feasibility of this method was demonstrated using the simulated deformation data of the simple inclusion problem. The proposed method seems promising for the quantitative differential diagnosis on the lesion in the tissue in vivo.

Algorithms↗
PubMed1990

Characterization of recombinant human aromatic L-amino acid decarboxylase expressed in COS cells.

The expression vector containing the full-length cDNA of human aromatic L-amino acid decarboxylase (EC 4.1.1.28) was transfected in COS cells by a modified calcium phosphate coprecipitation method. The cells transfected with plasmids that had a true direction of the cDNA gave a major immunoreactive band at 50 kDa. This expressed enzyme catalyzed the decarboxylation of L-3,4-dihydroxyphenylalanine (L-DOPA), L-5-hydroxytryptophan (L-5-HTP) and L-threo-3,4-dihydroxyphenylserine. The optimal pH of the enzyme activity with L-DOPA as a substrate was 6.5, whereas the enzyme had a broad pH optimum when L-5-HTP was used as a substrate. Addition of pyridoxal phosphate to the incubation mixture greatly enhanced the activity for both L-DOPA and L-5-HTP.

5-Hydroxytryptophan↗
PubMed1989

Inhibition of a transplantable pancreatic carcinoma by castration and estradiol administration in rats.

Influence of sex steroids on the growth of an azaserine-induced transplantable rat pancreatic carcinoma, DSL-2, was studied. This established transplantable tumor has been maintained in syngeneic rats. Inbred male Lewis rats were pretreated with castration and s.c. implantation of 1.0-mg 17 beta-estradiol (CAS: 50-28-2; estradiol) pellets at 7 weeks of age. Tumor cells were inoculated s.c. on the back of intact male, castrated male, or 17 beta-estradiol-treated castrated male rats. Additional male rats served as non-tumor-bearing controls. There was no difference in the body weight between tumor-bearing and non-tumor-bearing male rats. A distinct difference in the tumor growth was observed in variously conditioned recipients. In castrated male hosts, the serum testosterone levels and the epididymis weights were significantly decreased, and the tumor weights were significantly less as compared to intact control hosts. Additional pretreatment with 17 beta-estradiol caused a markedly slower growth of tumors and increases of the serum 17 beta-estradiol levels and the pituitary weights in castrated male recipients. The remarkable response of tumor growth to castration was also observed in a fast-growing tumor derived from DSL-2. Moreover, close positive relationships between tumor weights and the activities of both serum amylase and lipase were observed. Results showed that the pretreatment with castration alone or in combination with 17 beta-estradiol treatment was able to inhibit the growth of the transplantable tumor. In addition, tumor cells had an ability to produce amylase and lipase, and the amount of enzymic activity was related to the tumor volume. Thus, these data indicate that the transplantable rat pancreatic carcinoma retains physiological function. Our previous study has shown the modulation by sex steroids of azaserine-induced preneoplastic lesions of pancreas in rats. Therefore, androgens and estrogens may play key roles as promoters and inhibitors during the process of pancreatic carcinogenesis.

Amylases↗
PubMed1989

Inhibitory effects of estrogen and castration on the early stage of pancreatic carcinogenesis in Fischer rats treated with azaserine.

Effects of sex steroids on pancreatic carcinogenesis during the early stage were studied in azaserine-treated rats of both sexes. Fischer rats were given weekly i.p. injections of azaserine (30 mg/kg) [CAS:115-02; diazoacetate serine(ester)] at 2 and 3 weeks of age and were divided into six groups. Castration, ovariectomy, and s.c. implantations of either a 0.3-mg or a 1.0-mg 17 beta-estradiol (CAS:50-28.2; estradiol) pellet were performed at 7 weeks of age. The groups were as follows: group 1, intact male; group 2, castrated; group 3, castrated plus 0.3 mg estradiol; group 4, castrated plus 1.0 mg estradiol; group 5, ovariectomized; and group 6, intact female. Rats were killed 4 months after the last injection of azaserine. Azaserine treatment induced atypical acinar cell foci and nodules (AACN) in both sexes. The acidophilic AACN are considered preneoplastic lesions. An apparent sex difference was observed; the number of acidophilic AACN was greater in male rats than in female rats. Castration caused a significant decrease in both the serum testosterone levels and the number of acidophilic AACN, which were comparable to those in ovariectomized female rats. Furthermore, when estradiol treatment was administered to the castrated male rats, a linear decrease in the number of acidophilic AACN and an elevation in the serum estradiol levels were observed and were dose dependent. There were also positive relationships between estradiol treatments and the mean pituitary and pancreas weights. These results showed that estradiol treatment and the drop in testosterone levels caused by castration were highly effective in inhibiting the development and growth of preneoplastic lesions of the pancreas of the rats treated with azaserine. This estradiol effect was dose dependent. The present study, therefore, provides evidence that estrogen may act as an inhibitor and androgen as a promoter in the early stage of pancreatic carcinogenesis in rats.

Animals↗
PubMed1988

Changes in plasma levels of prolactin and estradiol, nutrient intake, and time spent nesting during the incubation phase of broodiness in the Chabo hen (Japanese bantam).

The plasma concentrations of prolactin (PRL) and estradiol, time spent nesting, consumption of feed and water, body weight, and hematocrit were measured during egg laying, incubating, and brooding of the chicks in a Japanese strain of dwarf bantam hen, Chabo. Plasma levels of PRL increased before incubation, were maintained at high levels during incubation, and decreased rapidly at the onset of hatching the young. The concentration of estradiol decreased before incubation and was maintained at low levels when circulating levels of PRL were high. During incubation, hens spent greater than 95% of the day on the nest, reduced their daily intake of feed and water by 63 and 78%, respectively, and decreased their body weight by 19% by the end of incubation. Thus, Chabo hens show a mode of incubation behavior similar to that reported in larger chickens. The temporal changes between nutrient intake and plasma levels of PRL at the start and end of incubation behavior suggested that changes in nutrient intake may not cause changes in the concentration of PRL, whereas the association between increased levels of PRL and decreased levels of estradiol suggested that they may be causally associated. Plasma levels of PRL also appeared to be associated with time spent on the nest.

Animals↗
PubMed1986

The presence of catechol-o-methyltransferase activity in separately cultured cerebromicrovascular endothelial and smooth muscle cells.

The activity of catechol-o-methyltransferase (COMT) was investigated in cultured and propagated cerebromicrovascular endothelial and smooth muscle cells using high performance liquid chromatography and immunocytochemistry. The existence of COMT was detected in both cell types. The demonstration of this enzyme activity in the cerebromicrovascular smooth muscle cells, in addition to the endothelium, indicates that the enzymatic barrier to catecholamine is not limited to capillaries, the main constituents of the blood-brain barrier.

Animals↗
PubMed1986

Characterization of histamine release in digitonin-permeabilized rabbit platelets.

To manipulate the intracellular milieu of rabbit platelets, permeabilization was performed using digitonin. Permeabilized platelets showed dose-dependent release of histamine, which was stored in granules of rabbit platelets, in response to extracellular calcium ion. As PMA stimulated the release reaction in digitonin-permeabilized platelets, the protein kinase C system, which regulates metabolic processes and cell reactions in intact platelets, was revealed to be working. Cupric phenanthroline also released histamine from permeabilized rabbit platelets dose-dependently, and dithiothreitol inhibited the release strongly. Since cupric phenanthroline is a mild oxidant which catalyzes the formation of disulfide bridges, as in the case of Ca2+-ATPase of sarcoplasmic reticulum, the results suggested that protein cross-linking is implicated in the regulation of the release reaction in permeabilized rabbit platelets.

Adenosine Triphosphate↗
PubMed1985

Inhibition by 3-amino-1H-1,2,4-triazole of hepatic tumorigenesis induced by diethylstilbestrol alone or combined with N-nitrosobutylurea in WF rats.

Six groups of inbred male WF rats were castrated at 40 days of age. Group 1 was given no further treatment; groups 3-6 received sc implantations of 5.0 mg diethylstilbestrol [(DES) CAS: 56-53-1]. At 50-55 days of age, groups 5 and 6 were given drinking water containing 5.0 mg N-nitrosobutylurea [(NBU) CAS: 869-01-2] per day for 30 days. After the termination of NBU treatment, groups 2, 4, and 6 were given 3-amino-1H-1,2,4-triazole (AT), considered an inhibitor of hydroperoxidases, in the drinking water throughout the experiment. Castrated male rats or rats castrated and treated with AT alone developed neither hepatic tumors nor pituitary tumors. The hepatic tumor incidence, the size and total number of hepatic tumors, and the mean liver weight were significantly reduced in rats given the DES-NBU combination and slightly reduced in rats given DES alone when AT was administered. In contrast, AT treatment did not change the pituitary tumor incidence and the mean pituitary weight. The thyroid gland weights were approximately 7-44 times greater in AT-treated groups than those in each corresponding control group. These data indicate that AT inhibited hepatic but not pituitary tumorigenesis and caused enlargement of the thyroid gland. The present study, therefore, provides evidence that the metabolic activation of DES by oxidation is involved in rat liver carcinogenesis.

Amitrole↗
PubMed1984

Preventive effects of antioestrogen on mammary and pituitary tumorigenesis in rats.

Six groups of inbred male Wistar/Furth (WF) rats were castrated at 40 days of age and group I received no further treatment. Groups 3 and 5 received 5.0 mg diethylstilboestrol (DES) pellets. Groups 4 and 6 were given both DES and 5.0 mg anti-oestrogen (antiE) clomiphene citrate pellets. At 50-55 days of age groups 2, 5, and 6 were exposed daily to drinking water containing 5.0 mg N-nitrosobutylurea (NBU), for 30 days. None of the castrated rats given NBU alone developed mammary or pituitary tumours (MT, PT). When antiE was administered, both MT and PT incidences were reduced in rats given DES alone or in combination with NBU. Furthermore, in antiE-treated rats receiving DES and NBU the mean number of MT per rat was also significantly decreased. Similarly a marked reduction in the mean pituitary weight was observed in antiE-treated groups. These results indicate that antiE treatment was effective in the prevention of both mammary and pituitary tumorigenesis in rats receiving DES alone or receiving a combination of DES and NBU, and its inhibitory effect on mammary tumorigenesis may be mainly due to competitive antagonism for DES-induced pituitary tumorigenesis by antiE.

Animals↗
PubMed1984

Inhibitory effect of antiestrogen on hepatic tumorigenesis in WF rats treated with diethylstilbestrol alone or in combination with N-nitrosobutylurea.

Four groups of inbred male WF rats were castrated and received sc implantations of diethylstilbestrol [(DES) CAS: 56-53-1; alpha,alpha'-diethyl-4,4'-stilbenediol] at 40 days of age. Group I was given no further treatment; groups II and IV were treated with antiestrogen (AntiE) clomiphene citrate simultaneously with DES treatment. At 50-55 days of age, groups III and IV were given drinking water containing N-nitrosobutylurea [(NBU) CAS: 869-01-2; 1-butyl-1-nitrosourea] for 30 days. Castrated male rats or rats castrated and treated with NBU alone developed neither hepatic tumors (HT) nor pituitary tumors (PT). When AntiE was administered, incidences of HT and PT, size and the total number of HT, and mean pituitary weight were significantly reduced in rats given DES alone and in rats given DES with NBU. AntiE treatment changed the distribution in the histologic classification of hepatocellular lesions: Neoplastic nodules, instead of hepatocellular carcinomas, were predominant. The results indicate that AntiE was effective in the inhibition of hepatic and pituitary tumorigenesis associated with DES treatment. Our previous study has shown that prolactin was not involved in this hepatic tumorigenesis. Therefore, these studies provide evidence that the carcinogenic effect of DES on the liver cell is direct and that HT are regulated in development and growth by AntiE treatment.

Animals↗
PubMed1984

Effects of 17 beta-estradiol and diethylstilbestrol on concurrent development of hepatic, mammary, and pituitary tumors in WF rats: evidence for differential effect on liver.

17 beta-Estradiol [(E2) CAS: 50-28-2; estradiol] and diethylstilbestrol [(DES) CAS: 56-53-1; alpha-alpha'-diethyl-4,4'-stilbenediol] were compared to determine their tumor-inducing abilities in tissue. After castration at 40 days of age, inbred male WF rats received a pellet of either 5.0 mg DES or 5.0 mg E2. Approximately half of the rats that had been given DES or E2 were further given at 50-55 days of age 5.0 mg N-nitrosobutylurea [(NBU) CAS: 869-01-2; 1-butyl-1-nitrosourea] in their drinking water each day for 30 days. None of the castrated rats given E2 alone developed hepatic tumors (HT). Even further addition of NBU did not elicit any HT. Conversely, E2 treatment as well as DES treatment, whether administrated alone or in combination with NBU, resulted in an increase in the incidence of pituitary tumors (PT) and in the mean pituitary weight. The data indicate that E2 was ineffective in inducing HT in castrated male rats, whereas E2 showed an ability to induce PT similar to that of DES. In addition, E2 was not as able to induce as many mammary tumors as DES was able to induce. There was no significant synergism between E2 and NBU in contrast to that between DES and NBU in mammary tumorigenesis, whereas these two estrogens had a similar effect in causing an increase in the pituitary weight. This study, therefore, suggests that the carcinogenic effect of estrogens may not always correlate with their estrogenic effect and further confirms the noninvolvement of prolactin in hepatic tumorigenesis.

Animals↗
PubMed1983

Induction of hepatic tumors by diethylstilbestrol alone or in synergism with n-nitrosobutylurea in castrated male WF rats.

Inbred male WF rats were castrated at 40 days of age and divided into 5 groups. Group I was given no further treatment. Groups III, IV, and V received pellet implants of 5.0 mg diethylstilbestrol (DES) concurrently with castration. At 50-55 days of age, groups II, IV, and V were given drinking water containing 5.0 mg N-nitrosobutylurea (NBU) per day for 30 days (subthreshold dose). At the termination of NBU treatment, group V further received daily sc injections of 2-bromoergocryptine (CB-154; 0.4 mg/100 g body wt) four times a week throughout the experiment. None of castrated rats or rats castrated and treated with NBU alone developed hepatic tumors (HT) and pituitary tumors (PT). Incidences of HT and PT in groups III, IV, and V were 4/9 (44%) and 7/9 (78%), 15/17 (88%) and 12/17 (71%), and 17/20 (85%) and 4/20 (20%), respectively. The treatment of DES alone resulted in the concurrent development of HT and PT in castrated male rats (group III), and further NBU treatment significantly increased the incidence of HT (group IV). CB-154 treatment did not change the incidence of HT, the number of HT per rat, and the liver weight, although it significantly reduced the incidence of PT, the pituitary weight, and the serum prolactin level in castrated male rats given DES and NBU (group V). These results indicate that DES itself had a direct carcinogenic effect on the liver; this effect was not mediated by prolactin, and NBU increased the effect of DES in this process.

Animals↗
PubMed1983

Suppression of diethylstilbestrol and N-nitrosobutylurea-induced mammary and pituitary tumorigenesis in rats by prolonged treatment with 2-bromoergocryptine.

Inbred male W/Fu rats were castrated at 40 days of age (24) and divided into five groups. Group I was given no further treatment. Groups II, IV, and V received pellet implants of 5.0 mg diethylstilbestrol (DES) concurrently with the castration. At 50 to 55 days of age, Groups II, IV, and V were given drinking water containing 5.0 mg N-nitrosobutylurea (NBU)/day for 30 days. This amount does not induce mammary tumors (MTs) in castrated male rats (24) or in female rats (31). At the termination of NBU treatment, Group V received further daily s.c. injections of 2-bromoergocryptine (CB-154; 0.4 mg/100 g body weight) four times/week throughout the experiment. None of the castrated rats or rats castrated and treated with NBU alone developed MT or pituitary tumors (PTs). Incidences of MT and PT in Groups III, IV, and V were three of nine (33%) and seven of nine (78%), 15 of 17 (88%) and 12 of 17 (17%), and three of 20 (15%) and four of 20 (20%), respectively. The treatment with DES alone resulted in the concurrent development of MT and PT in castrated male rats (Group III), and further NBU treatment markedly accelerated the development and growth of MT (Group IV). CB-154 treatment profoundly reduced the incidences of both MT and PT in castrated male rats given DES and NBU (Group V). This treatment also depressed the increase in the number of MT per rat with MT, the pituitary and epididymis weights, and the serum prolactin levels caused by DES treatment. These results indicate that prolonged treatment with CB-154 was effective in the suppression of the concurrent tumorigenesis of mammary and pituitary glands, and the elevation of circulating prolactin levels, by counteracting the continuous stimulatory action of DES. In addition, CB-154 was able to reverse DES-enhanced growth of the epididymis in castrated male rats, suggesting a direct action of prolactin.

Animals↗
PubMed1981

Immunological reaction between sera from neutron-irradiated W/FU rats and mouse mammary tumor virus.

Sera from W/Fu rats from the presence of anti mouse mammary tumor virus (MMTV) antibodies were examined by the use of an immunofluorescence (IF) test and an immune adherence hemagglutination (IAHA) test. Sera from W/Fu rats subjected to neutron irradiation or neutron irradiation followed by grafting of pituitary tumor (MtT) as a source of prolactin gave a positive IF reaction with mouse mammary tumor cells (MMT) producing type-A and type-B virus particles. Nine out of 20 (45.0%) sera from rats given irradiation alone, 17 out of 25 (68.0%) sera from rats subjected to irradiation followed by grafting of MtT and 8 out of 10 (80%) sera from rats given only grafting of MtT gave a positive reaction with the cells, whereas 5 out of 19 (26.3%) sera from normal rats showed a positive reaction with the cells. The specificity of the reaction was confirmed by the distribution pattern of specific fluorescence in MMT cells and by absorption experiments with suitable materials. The results of the IAHA test also showed that some sera from W/Fu rats reacted specifically with purified MMTV, although the incidence of appearance of antibodies in rat sera as detected by IAhA test was low as compared with that detected by IF tests. The IAHA titers of positive rat sera ranged from 1:8 to 1:128. Furthermore, the above results suggest that MtT grafting into W/Fu rats, whether or not they are subjected to neutron irradiation, results in an increase in the frequency of rats carrying antibodies against MMTV.

Animals↗