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Biomedical subjects

H Sumiya

Publications and source records attributed to H Sumiya.

At least 73 records · Page 4Linked to original sources
PubMed1988

Quantitative assessment of cerebral blood flow using technetium-99m-hexamethyl-propyleneamine oxime: Part I, Design of a mathematical model.

To design a mathematical model for quantifying cerebral blood flow using 99mTc-hexamethyl-propyleneamine oxime (HM-PAO), basic studies were performed in animals and human volunteers. Microautoradiography revealed that HM-PAO crossed the blood-brain barrier. Thin layer chromatographic studies demonstrated the rapid disappearance of free HM-PAO in the brain tissue. Back diffusion from brain to blood was found negligible. From these observations, the familiar microsphere model was employed in the measurements of blood flow with HM-PAO. This, however, resulted in much lower flow values than simultaneously obtained values with the labeled microspheres. This underestimation was ascribed to the high affinity of HM-PAO to blood cells and serum protein. Taking the binding of HM-PAO to blood components into consideration, the following model equation was designed for quantifying cerebral blood flow: Ce(t) = Ca(t)-kCa(t)*exp(-kt), Cb(T) = F integral of T0 Ce(t)dt, where Ce and Ca are the free HM-PAO concentration in the intravascular space and the arterial whole-blood concentration of HM-PAO, respectively, as a function of time (t), Cb is the brain activity concentration, k is the rate constant for the binding of HM-PAO to the blood components, F is the blood flow value, T is time of measurement, and * denotes the operation of convolution. In clinical studies, Ca(t) and Cb(T) are obtainable from a dynamic single photon emission computerized tomographic study of the brain and multiple arterial blood sampling, respectively. The values for F and k can be estimated using a nonlinear least squares fitting method.

Animals↗
PubMed1988

Determination of flow and rate constants in a kinetic model of [99mTc]-hexamethyl-propylene amine oxime in the human brain.

The values for flow and rate constants for a kinetic model of [99mTc]-hexamethylpropyleneamine oxime (HM-PAO) distribution in the human brain were determined. The single-pass extraction ratio of HM-PAO was also determined in the rat brain by the indicator diffusion method; a value of 0.90 +/- 0.02 (mean +/- SEM, n = 5) was obtained. Time course data of brain activity and arterial blood activity of the tracer were fitted to a four compartment model: Values of blood flow and the first-order rate constants for backdiffusion of the diffusible tracer from brain to blood (k2), conversion of the lipophilic tracer to the hydrophilic one in brain (k3), and conversion of the diffusible tracer to the nondiffusible one in blood (k5) were determined. Conversion of hydrophilic tracer back to a lipophilic form in both blood and brain was assumed to be negligible during the course of the experiment. The values obtained for blood flow, k2, and k3 were, respectively, 0.40 +/- 0.03 ml/g/min, 0.38 +/- 0.04 min-1, and 0.92 +/- 0.05 min-1 in the gray matter (n = 4), and 0.23 +/- 0.01 ml/g/min, 0.17 +/- 0.01 min-1, and 1.01 +/- 0.05 min-1 in the white matter (n = 2) in patients with cerebrovascular disorder. The k5 value was 1.14 +/- 0.06 min-1 (n = 4). These experimentally determined values agree well with the theoretical ones previously reported by Lassen et al. The results suggest the relative constancy of the k3 and k5 values and the more prominent initial backdiffusion of the lipophilic HM-PAO from brain to blood in high flow regions compared to low flow regions.

Animals↗
PubMed1988

Direct autoradiographic comparison of 99Tcm-HMPAO with 125I-IMP in experimental brain ischaemia.

Local cerebral blood flow (LCBF) images of HMPAO and IMP were directly compared in experimental brain ischaemia in the same rats using a double-tracer autoradiographic technique. Both images were identical in distribution throughout the whole flow areas. However, LCBF values were much lower in HMPAO than in IMP. The results suggest that HMPAO acts as a chemical microembolus in rat brain in both low and high flow areas; however, a quantitative flow measurement is difficult in an HMPAO study.

Amphetamines↗
PubMed1988

[Lectin-binding sugar chain in bladder tumors].

We studied the lectin binding patterns of 40 initial superficial and 10 subsequent invasive bladder tumors by the avidin-biotin-peroxidase complex (ABC) method using the following biotin-labeled lectins: PNA, DBA, UEA-I, BS-I, ConA and WGA. We observed the relationship between lectin binding and subsequent course of initial superficial tumors, grade and stage (T). DBA or WGA staining tumors and Con A negative tumors revealed no recurrence or superficial recurrence. Low grade tumors were DBA or BS-I positive and high grade tumors were ConA positive. Low staging tumors possessed DBA or WGA positiveness and high staging tumors had ConA positiveness. From these results we considered that negative staining of WGA or DBA, or positive staining of ConA was a change accompanying the malignant potentiality.

Adult↗
PubMed1988

[Prostatic carcinoma. I: Androgen dependency of prostatic carcinoma].

Endocrine therapy, which consists of orchiectomy followed by administration of large doses of estrogen, then a reduced amount of estrogen, has been applied as the main treatment for stage D2 prostatic cancer. Alternatively, anti-androgen is used for elderly patients or those with cardiovascular disorders. Survival rate with endocrine therapy at 5 and 10 years was 35% and 16%, respectively. Therefore, in Japan, a better survival is shown than that reported in western countries using much smaller doses of estrogen. Most of the side effects caused by estrogen are not serious. Side effects caused by anti-androgen are few except for loss of libido. At the start of treatment, more than 80% of patients showed a response, but gradually relapse occurred and only 20% were well controlled 5 years after the start. Factors influencing the survival were pathological grade, response to endocrine therapy judged by the level of prostatic acid phosphatase 4 weeks after the start, and R1881 (methyltrienolone)-binding protein observed histochemically. The latter protein was also correlated with the grade and response to endocrine therapy. Relapse after endocrine therapy might be attributable to adaptation or mutation progressing to androgen-independent cells. Using SC 115, an androgen-dependent mouse tumor, these two types of relapse were demonstrated. Gradual progression to undifferentiated cancer was noticed between pretreatment biopsy and autopsy. Relapse in human prostatic cancer may thus be partly due to genetic change to a resistant clone.

Androgen Antagonists↗
PubMed1987

Grade and histochemical R-1881 binding in prostatic cancer.

Comparison of the grades classified by Gleason with R-1881 binding which was attributable to total androphilic proteins in tissues was performed in 42 untreated and 13 relapsed prostatic cancers. Increasing malignancy correlated with loss of staining on R-1881 binding when examined both in primary pattern and in individual tumor cell clusters. In relapsed cancer, however, there was no R-1881 binding irrespective of any grades.

Estrenes↗
PubMed1987

Benign prostatic hypertrophy in a young male.

A 20-year-old male with complaints of dysuria and a sense of residual urine was diagnosed as having benign prostatic hypertrophy. He was treated by suprapubic prostatectomy. Benign prostatic hypertrophy in young men is very rare; this case seems to be the largest (380 g) among juvenile benign prostatic hypertrophy reported in the literature so far.

Adult↗
PubMed1987

A new noninvasive quantitative assessment of cerebral blood flow using N-isopropyl-(iodine 123)p-iodoamphetamine.

The use of a nomogram is described as a new noninvasive quantitative assessment of cerebral blood flow using N-isopropyl-(123I)p-iodoamphetamine (IMP) and single-photon emission computed tomography. The nomogram was constructed from a computer analysis of the flow value relative to varying washout rate of brain activities between early and late tomographic images, and partition coefficient between brain tissue and blood. The validity of this method was evaluated in normal volunteers and in patients with cerebrovascular disorders by comparing the cortical flow values (Y) estimated from the IMP-nomogram with initial slope indices (X) by the 133Xe inhalation method. A significant correlation (N = 42, r = 0.88, P less than .001) was demonstrated between them, and the regression line was Y = 1.6X-7. A development and confirmation of this method made it possible to measure flow values noninvasively with the use of IMP.

Adult↗
PubMed1986

Changes in the volume and histology of retractile testes in prepubertal boys.

Testicular development was studied in prepubertal boys with retractile testes. Testicular volume, the diameter of the seminiferous tubules and the number of spermatogonia in the tubules were decreased in cases of unilateral retractile testis, when compared with values for the contralateral normally descended testis. On the other hand, in patients with a unilateral retractile testis and contralateral inguinal testis, there was no difference in the developmental parameters between the two testes. These results suggest that the retractile testis has developmental failures characteristic of a cryptorchid testis and therefore requires orchiopexy.

Child↗
PubMed1986

Histochemical study of R1881-binding protein, prostatic acid phosphatase, prostate-specific antigen, and r-seminoprotein in prostatic cancer.

A histochemical study on R1881-binding protein, prostatic acid phosphatase (PAP), prostate-specific antigen (PA) and r-seminoprotein was conducted. These parameters and histologic grades were compared to each other and with the responsiveness to endocrine therapy. A good correlation was found between histologic grade and presence or absence of R1881-binding protein in the tissue. Presence or absence of R1881-binding protein as well as histologic grade correlated well with responsiveness to endocrine therapy. Positive staining patterns of PAP, PA, and r-seminoprotein in the tissues were similar to each other, particularly between PA and r-seminoprotein. However, no correlation was found between the histologic grade and ratios of PAP, PA or r-seminoprotein-positive cells. Nor was any correlation seen between the ratio of these marker-positive cells and responsiveness to endocrine therapy.

Acid Phosphatase↗