Biomedical subjects

S Okuno

Publications and source records attributed to S Okuno.

At least 181 records · Page 10Linked to original sources

PubMed1993

[Chronic encapsulated intracerebral hematoma associated with cavernous angioma: case report and review of the literature].

We reported a case of chronic encapsulated intracerebral hematoma associated with cavernous angioma. A 71-year old female was admitted with a history of frontal headaches at intervals of about 3 months for the last one year. Plain CT scan showed a round mass of heterogeneous high density in the left medial frontal lobe. The outer surface of the mass was enhanced with contrast material. MRI demonstrated the mass as a high signal intensity on T1-weighted image and low intensity with laminated structure on T2-weighted image. MR angiogram depicted the mass as a mottled high signal intensity. The left internal carotid artery angiogram revealed no abnormal shadows and vessels. These findings suggested some form of a thrombus although its underlying pathogenesis was unclear. On January 20, 1992, a bifrontal craniotomy was performed. A whitish well-demarcated mass was seen in the left cingulate gyrus through a small corticotomy. We could not identify any branches feeding the mass. The cross-section of the mass disclosed a uniform thrombus encapsulated by a thick wall. Histological studies of the wall confirmed a cavernous angioma within the outer collagenous layers. Chronic encapsulated hematoma, which was first reported by Hirsh in 1981, has represented a separate entity and 25 such cases have been documented in the literature. These reports suggested that the compression and/or destruction of the surrounding tissue caused by the hemorrhage would mask the existence of the cavernous angioma or vascular malformation. If an encapsulated hematoma were encountered during an operation, surgeons should pay attention not to overlook the residual capsule encompassing the cavernous angioma or vascular malformation.

Adolescent↗

PubMed1992

[A case of esophageal carcinoma with hypercalcemia caused by PTH-rP--the effect of therapy on the bone and calcium metabolism].

The changes in the bone and in calcium metabolism during cisplatin or bisphosphonate administration is reported in a 50-year-old patient with esophageal carcinoma who had humoral hypercalcemia of malignancy (HHM). Laboratory findings on admission showed that ionized calcium was 1.65mmol/L, phosphorus was 2.4mg/dl, and PTH-rP was 151pmol/L, without any evidence of bone metastasis. After admission, cisplatin and/or bisphosphonate were administrated for hypercalcemia. These administrations ameliorated serum ionized calcium, urinary pyridinoline and hydroxyproline level within a few days. Although cisplatin administration decreased the serum osteocalcin level, bisphosphonate administration kept up the level, suggesting that bisphosphonate maintained bone formation and cisplatin decreased its formation. The discrepancy may be due to the coupling with the reduction of bone resorption and/or direct toxic effect on osteoblasts during cisplatin administration, and preservation of osteoblastic activity during bisphosphonate administration. Cisplatin and bisphosphonate may have different effects on bone formation. Serum 1,25(OH)2D level was slightly decreased or unchangeable after cisplatin administration, although the level was increased after bisphosphonate administration. Direct toxic effect on 1 alpha-hydroxylase of the kidney or increase in phosphrous level may explain the change of 1,25(OH)2D after cisplatin administration. These results suggested that cisplatin and bisphosphonate have the same effect of preventing bone resorption but different effects on bone formation and/or serum 1,25(OH)2D level.

Bone Resorption↗

PubMed1992

Synthesis of omega-(methoxycarbonyl)alkyl and 9-(methoxycarbonyl)-3,6-dioxanonyl glycopyranosides for the preparation of carbohydrate-protein conjugates.

omega-(Methoxycarbonyl)alkyl glycopyranosides of D-mannose having C4, C7, C9, C12, and C15 carbon chains, L-fucose and 2-acetamido-2-deoxy-D-mannose having C7 and C9 carbon chains, D-xylose and 2-acetamido-2-deoxy-L-fucose having a C9 carbon chain, and 9-(methoxycarbonyl)-3,6-dioxanonyl glycopyranosides of D-mannose, 2-acetamido-2-deoxy-D-mannose, and L-fucose were synthesized as intermediates for coupling to human serum albumin in order to examine the effect of chain length and hydrophobicity of the spacer arm on the binding specificity of lectins. 8-(Methoxycarbonyl)octyl glycosides of beta-D-Man-(1----2)-alpha-D-Man, alpha-D-Man-(1----2)-alpha-D-Man, alpha-D-ManNAc-(1----2)-alpha-D-Man, beta-D-GlcNAc-(1----2)-alpha-D-Man, and their 6-O-positional isomers, beta-D-Man-(1----6)-alpha-D-Man, alpha-D-Man-(1----6)-alpha-D-Man, alpha-D-ManNAc-(1----6)-alpha-D-Man, and beta-D-GlcNAc-(1----6)-alpha-D-Man, were also synthesized.

Carbohydrate Sequence↗

PubMed1992

Dibutyryl cAMP enhances the effect of 1,25-dihydroxyvitamin D3 on a human promyelocytic leukemia cell, HL-60, at both the receptor and the postreceptor steps.

1,25-Dihydroxyvitamin D3 (1,25-(OH)2D3) induces differentiation of a human promyelocytic leukemia cell line, HL-60, into monocytes/macrophages, and 25-hydroxyvitamin D3- and 1,25-(OH)2D3-24-hydroxylase activities in HL-60 mitochondria via a steroid-hormone receptor mechanism. Dibutyryl cyclic adenosine monophosphate (dbcAMP), a granulocyte inducer, significantly augmented the differentiation-inducing effect of 1,25-(OH)2D3 along the monocyte/macrophage pathway. Furthermore, dbcAMP significantly potentiated the effect of 1,25-(OH)2D3 on HL-60 cells to hydroxylate 1,25-(OH)2[26,27-3H]D3 to form 1,24,25-(OH)3[26,27-3H]D3. DbcAMP seemed to augment the effect of 1,25-(OH)2D3 in part through upregulation of the 1,25-(OH)2D3 receptor, because 10(-7) M dbcAMP increased 1,25-(OH)2D3 receptor levels approximately 2.3-fold, which was similar to a 1.9-fold augmentation by the same concentrations of dbcAMP of 1,25-(OH)2D3-induced cell characteristics to hydroxylate C-24 of 1,25-(OH)2[26,27-3H]D3. However, dbcAMP is also known to enhance HL-60 cell differentiation caused by other differentiation inducers. We have established another HL-60 clone which acquires resistance to 1,25-(OH)2D3 in the induction of cell differentiation by a defect at the postreceptor step, as reflected by resistance to other differentiation inducers, such as retinoic acid and dimethyl sulfoxide. Even in this resistant clone, dbcAMP significantly enhanced the differentiation-inducing effect of 1,25-(OH)2D3. Of interest, this clone showed resistance to dbcAMP in the induction of cell differentiation. Furthermore, we have demonstrated that intracellular cAMP levels were significantly lower in uremic serum-treated cells than in cells treated with normal human serum and that a significant positive correlation was found between intracellular cAMP levels and 1,25-(OH)2D3-induced cell differentiation. These data indicated that the intracellular cAMP level is one of the major determinants of 1,25-(OH)2D3-induced HL-60 cell differentiation and that dbcAMP could enhance the effects of 1,25-(OH)2D3 on HL-60 cells not only by increasing 1,25-(OH)2D3 receptor levels but also at the postreceptor step.

Bucladesine↗

PubMed1992

Autoantibodies to 64,000-M(r) islet cell protein in long-term type 1 (insulin-dependent) diabetic patients.

Autoantibodies to the 64,000-M(r) (64K) islet cell protein, identified as glutamic acid decarboxylase, were assayed in 46 Type 1 (insulin-dependent) diabetic patients with a disease duration of more than 5 years. Of 46 Type 1 diabetic patients, 18 (39.1%) were found to be positive for 64K antibodies and 12 of these patients had been diagnosed with autoimmune thyroid disease. Serum C-peptide levels were not detectable in 15 of 18 patients positive for 64K antibodies. The samples were also tested for titres of islet cell antibodies. Islet cell antibodies were detected in 15 (32.6%) of the 46 patients and all the islet cell antibody positive patients were also found to be positive for 64K antibodies. Furthermore, of these 15 patients 12 had previously been diagnosed with autoimmune thyroid disease. A correlation between levels of 64K antibodies and islet cell antibody titre revealed that higher levels of 64K antibodies were observed in patients who had higher islet cell antibody titre. These results demonstrate that most long-term Type 1 diabetic patients with 64K antibodies were also positive for islet cell antibodies complicated by autoimmune thyroid disease.

Adult↗

PubMed1992

Partial protection of 1 alpha-hydroxyvitamin D3 against the development of diabetes induced by multiple low-dose streptozotocin injection in CD-1 mice.

1 alpha-Hydroxyvitamin D3 (1 alpha-OH-D3), a precursor of active vitamin D3, 1 alpha,25-dihydroxyvitamin D3, was tested in CD-1 mice for its in vivo effect against the development of diabetes induced by administering multiple low doses of streptozotocin (STZ). Daily intraperitoneal (IP) injections of 35 mg/kg body weight of STZ administered for 5 consecutive days to mice from 7 weeks of age induced a delayed-onset hyperglycemia, insulitis, and beta-cell degranulation in 26 of 28 mice. Only 12 of 29 mice developed diabetes when treated with simultaneous daily IP injections of 1 alpha-OH-D3 for 14 consecutive days, with diabetes defined as a plasma glucose level greater than 200 mg/dL. A daily dose of 0.3 micrograms/kg 1 alpha-OH-D3 also protected against the development of hyperglycemia in five of 13 mice, whereas 0.2 micrograms/kg 1 alpha-OH-D3 was ineffective, indicating a dose-related effect. Histological study showed that, among the 1 alpha-OH-D3-treated mice, the pancreatic islets of euglycemic mice showed neither massive islet infiltration nor beta-cell degranulation, whereas those of the hyperglycemic mice showed insulitis. However, when diabetes was chemically induced with a single high dose of STZ, the simultaneous administration of 1 alpha-OH-D3 to mice failed to protect against the development of hyperglycemia; all five mice so treated developed hyperglycemia. Their pancreatic islets did not show insulitis. Therefore, it is suggested that 1 alpha-OH-D3 may protect against the development of diabetes following administration of multiple low doses of STZ, probably via an immune mechanism.

Animals↗

PubMed1992

Regional differences in insulin receptor function in Werner's syndrome.

Werner's syndrome is a genetic disease characterized by premature aging and is often associated with glucose intolerance due to insulin resistance. The clinical manifestations in this syndrome are preferentially expressed in the face and acral regions without apparent involvement of the trunk. We compared insulin receptor binding and amino acid uptake of fibroblasts derived from the forearm that had sclerodermoid features, and from the abdomen that was apparently normal in a patient with Werner's syndrome. In normal controls, specific insulin binding was not different in forearm and abdomen-derived fibroblasts (10.72 +/- 2.11%, 10.40 +/- 1.27%, respectively). In the patient, however, specific insulin binding was reduced in the fibroblasts derived from the forearm compared with those derived from the abdomen (3.55%, 8.16%, respectively). Scatchard analysis revealed that the reduction in insulin binding of the forearm fibroblasts from the patient was due to a reduction in receptor number with no change in receptor affinity. The dose-response curve for insulin of alpha-aminoisobutyric acid (AIB) uptake is shifted to the right in the fibroblasts derived from the acral area. The results show that in a patient with Werner's syndrome, regional differences occur in fibroblast insulin receptor binding and function. This suggests early phenotypic expression of the genetic abnormality of insulin receptor function in these patients.

Abdomen↗

PubMed1992

Type 1 (insulin-dependent) diabetes mellitus with coexisting autoimmune thyroid disease in Japan.

Type 1 diabetes mellitus is known to be a heterogenous disease which is frequently complicated with other autoimmune thyroid diseases (AITD). The present study was designed to investigate the clinical characteristics and HLA antigens in Japanese Type 1 diabetic patients with AITD. Subjects were 25 Type 1 diabetic patients with AITD (13 Graves' disease and 12 Hashimoto's thyroiditis) and 32 Type 1 diabetic patients without AITD. Compared with Type 1 diabetic patients without AITD, age at onset of diabetes was later and positive ICA persisted much longer in the diabetic patients with AITD. Compared with normal controls, DR9 was increased in the patients with AITD, while DR4 was increased in those without AITD. Type 1 diabetic patients with AITD were characterized by the late onset of diabetes, persistent ICA and increased association with DR9. These results suggest that immunological and genetic heterogeneity may exist within Japanese Type 1 diabetic patients.

Adolescent↗

PubMed1992

Recurrent intracranial germinoma refractory to conventional irradiation: effective chemotherapy consisting of cisplatin and etoposide--case report.

Recurrent intracranial germinoma with multiple spinal metastases occurred in a 16-year-old male presenting with persistent headache and visual disturbances. Computed tomography revealed enhanced lesions in the pineal region, anterior horn, and infundibulum. Conventional irradiation achieved remission, but local recurrences requiring further irradiation occurred after 23 months. Magnetic resonance imaging showed multiple spinal metastases 11 months later. Partial removal of the spinal lesions gave a histological diagnosis of typical germinoma. Postoperatively, intracranial recurrences were again detected. Chemotherapy consisting of intravenous cisplatin and etoposide achieved remission and no recurrence has occurred for 12 months.

Adolescent↗

PubMed1992

Diaphragma sellae meningioma associated only with signs of hypopituitarism--case report.

A rare diaphragma sellae meningioma presenting only with signs of hypopituitarism occurred in a 54-year-old male. Preoperative magnetic resonance (MR) imaging clearly demonstrated a small lesion in the supradiaphragmatic area immediately beneath the optic chiasm, displacing the pituitary stalk laterally. Intraoperatively, the tumor was confirmed to be attached only to the posterior leaf of the diaphragma sellae. Histological examination revealed a transitional type meningioma. Such a small meningioma may be associated only with hypopituitarism, as compression is confined to the pituitary stalk, not affecting the optic pathways. MR imaging can demonstrate the clinicopathological features of this small but significant tumor.

Humans↗

PubMed1992

Magnesium deficiency enhances secretion of parathyroid hormone in normal and 5/6-nephrectomized uremic rats.

Hypercalcemia, rather than hypocalcemia, has been observed in conjunction with severe magnesium (Mg) depletion in rat, in contrast to the development of hypocalcemia in Mg deficiency in various animal models. In the present study, a possible involvement of parathyroid hormone (PTH) in the development of hypercalcemia in rat was studied by using a newly-developed sensitive and specific radioimmunoassay system for the determination of rat PTH. In normal rat model, hypercalcemia occurred in association with a decrease of serum phosphate levels in Mg deficiency. However, serum PTH levels were not suppressed despite the occurrence of hypercalcemia, suggesting PTH as an important factor for the development of hypercalcemia. Of interest, in 5/6-nephrectomized uremic model, hypocalcemia, rather than hypercalcemia, was observed in Mg-deficient rats. Serum PTH levels seemed to be higher, but not statistically significant probably due to a small number of rats. However, infusion study clearly demonstrated that PTH secretion was significantly increased in Mg-deficient uremic rats compared with Mg-replete counterparts. The reason for an increase of serum PTH responses might be explained by Mg depletion itself in addition to a fall in serum Ca levels, because infusion study revealed that the magnitude of the stimulation of PTH secretion was increased in Mg deficiency despite the similar degrees of changes in serum Ca levels and that the set point for the suppression of PTH secretion by Ca might be altered in Mg deficiency. Taken these data together, it was strongly suggested that Mg depletion might enhance PTH secretion in rat.

Animals↗

PubMed1992

[A case of intracranial germinoma responsive to amphotericin B].

A 20-year-old man was admitted to our institution complaining of gradually worsening motor weakness in the right extremities. On admission, the radiological examination revealed a mass located in the left parietal region. On April 4, 1988, a left fronto-parietal craniotomy was performed and the tumor was subtotally removed. The pathological findings of the surgical specimen confirmed no specific tumor, but the presence of a small mingled Candida glabrata supported the diagnosis of fungal granuloma. Amphotericin B (AmB) was administered intravenously for the later enlargement of the tumor. MRI 4 weeks after the beginning of this treatment demonstrated the tumor to be prominently decreased in size. At discharge 3 months later, there was no tumor except only a minimal one in the paraventricular region. However, the recurrence of the tumor was discovered again over the next 8 months. AmB was administered as before, but the tumor continued to be enlarged. In May, 1990, surgery was performed again, and the histological diagnosis was germinoma accompanied with considerable granulomatous reaction. Subsequently, local irradiation was given and complete remission was maintained up to the present time 8 months after irradiation. AmB is a polyene antifungal antibiotic, that has also been reported to enhance the response of antitumor drugs to some tumors on the basis of increased tumor cell permeability. Recent investigations revealed that AmB had immunoadjuvant properties mediated through activated lymphocytes and macrophages, which resulted in an increased host resistance against infectious diseases and even tumors in vivo or in vitro studies. We reported a rare case of intracranial germinoma which responded well to AmB probably through its own antitumor effect caused by immunoadjuvant properties. We discussed the possibility of AmB to be used as immunoadjuvant agent or in combination with other antitumor drugs for the effective treatment of some tumors.

Adult↗

PubMed1992

[Germinoma with granulomatous reaction arising from the corona radiata; case report and review of articles].

We report a rare case of germinoma with granulomatous reaction arising from the corona radiata. This 20-year-old man was admitted to our hospital complaining of progressive motor weakness on the right side. CT demonstrated a poorly demarcated high density area in the left corona radiata, which was heterogeneously enhanced after administration of contrast medium. Moreover, the continuity of the mass to the ventricular wall was confirmed on MRI. At the first operation, subtotal removal of the tumor was performed through a fronto-parietal craniotomy. The diagnosis for the specific neoplasm was not established histologically, but granuloma caused by fungal infection was the most likely cause of the lesion. We tried amphotericin B (AmB), and remission of the tumor was obtained. However, during the following 3 months, the size of the tumor gradually enlarged again. AmB was repeatedly administered, but this time the treatment was ineffective. Six months later, on May 21, 1990, the second operation was performed and histological examination revealed typical germinoma consisting of two-cell pattern. Subsequently, the patient underwent focal irradiation of 33 Gy to the tumor site, and the tumor completely disappeared. As intracranial germinomas are observed to be successfully cured by radiotherapy and/or chemotherapy, choice of the therapeutic management must be carefully determined according to the histological diagnosis, especially in young people. A variety of locations of germinomas and the accompanying granulomatous reactions could create some diagnostic confusion, so great care must be taken in the treatment of much intracranial germinomas.

Adult↗

PubMed1991

Different effects on activity caused by phosphorylation of tyrosine hydroxylase at serine 40 by three multifunctional protein kinases.

Tyrosine hydroxylase was maximally phosphorylated by protein kinase C, with a stoichiometry of 0.43 mol of phosphate/mol of tyrosine hydroxylase subunit at Ser40, and by calmodulin-dependent protein kinase II, with stoichiometries of 0.43 mol/mol at Ser40 and 0.76 mol/mol at Ser19, respectively, without undergoing any significant direct activation. In contrast, the enzyme was maximally phosphorylated with a stoichiometry of 0.78 mol of phosphate/mol of subunit at Ser40 by cAMP-dependent protein kinase, which resulted in a large activation of the enzyme (about 3-fold activation under the assay conditions). Incubation of the enzyme, which had previously been maximally phosphorylated by calmodulin-dependent protein kinase II, with protein kinase C under phosphorylating conditions resulted in no additional incorporation of phosphate into the enzyme, suggesting that both protein kinases phosphorylated Ser40 of the same subunits of the enzyme. Since tyrosine hydroxylase is thought to be composed of four identical subunits, the results may indicate that calmodulin-dependent protein kinase II or protein kinase C phosphorylates only two of the four subunits of the enzyme at Ser40 without affecting the enzyme activity and that cAMP-dependent protein kinase phosphorylates Ser40 of all four subunits of the enzyme molecule, causing a marked activation. Based on a linear relationship between phosphorylation and the resulting activation of the enzyme by cAMP-dependent protein kinase, possible mechanisms for the activation of the enzyme by the protein kinase are discussed.

Animals↗

PubMed1991

Studies on the generation of Ca2+/calmodulin-independent activity of calmodulin-dependent protein kinase II by autophosphorylation. Autothiophosphorylation of the enzyme.

The mechanism for the generation of the Ca2+/calmodulin (CaM)-independent activity of calmodulin-dependent protein kinase II (CaM-kinase II) by autophosphorylation was studied by characterizing the autothiophosphorylated enzyme, which is resistant to hydrolysis. When CaM-kinase II was incubated with adenosine 5'-O-(thiotriphosphate) at 5 degrees C, the incorporation of thiophosphate into the enzyme occurred rapidly, reaching a maximum level within a few minutes, in parallel with increase in Ca2+/CaM-independent activity. The maximum level was 1 mol of thiophosphate per mol of subunit of the enzyme, and the thiophosphorylation occurred exclusively at Thr286 in the alpha subunit and Thr287 in the other subunits of the enzyme. These results, taken together, indicate that the autothiophosphorylation of Thr286/Thr287 of each subunit is involved in the generation of the Ca2+/CaM-independent activity. The activity of the autothiophosphorylated enzyme, when assayed in the presence of Ca2+/CaM, showed the same kinetic properties as did the Ca2+/CaM-dependent activity of the original non-phosphorylated enzyme, but when assayed in the absence of Ca2+/CaM, it showed the same Vmax as the Ca2+/CaM-dependent activity but higher Km values for protein substrates. Thus, the phosphorylation of Thr286/Thr287 of the subunit of the enzyme by autophosphorylation appears to not only enhance the affinity of its substrate-binding site for the protein substrate, although it is lower than that of the enzyme activated by the binding of CaM, but also convert the active site to the fully active state.

Animals↗

PubMed1991

Immunoelectron microscopic study of tyrosine hydroxylase immunoreactive nerve fibers and ganglion cells in the rat adrenal gland.

The present immunocytochemical study used an antiserum to tyrosine hydroxylase (TH), the first enzyme in the biosynthetic pathway of catecholamines, and revealed TH immunoreactivity in the ganglion cells and in the varicose nerve fibers of the cortex and medulla in the rat adrenal gland. TH immunoreactive nerve fibers in the cortex and medulla contained large and small granular vesicles, and also small clear vesicles. The immunoreactive nerve fibers were in close apposition to cortical cells in the cortex and in apposition to smooth muscle cells of blood vessels in both the cortex and medulla. Furthermore, TH immunoreactive nerve fibers were sometimes in close apposition to pericytes of blood vessels in the cortex and chromaffin cells in the medulla. The present results suggest that the catecholaminergic nerve fibers in the rat adrenal gland may be both intrinsic and extrinsic in origin.

Adrenal Glands↗

PubMed1991

Production of islet cell antibodies from Epstein-Barr virus-transformed peripheral blood lymphocytes in type 1 (insulin-dependent) diabetic patients.

Islet cell antibodies are usually detected in the sera of almost all Type 1 (insulin-dependent) diabetic patients within several months after onset of the disease. The antibodies then disappeared quite early during the course of the disease. The present study was undertaken to detect islet cell antibody-producing clones in peripheral blood lymphocytes of Type 1 diabetic patients whose islet cell antibodies could not be detected in sera. Epstein-Barr virus-transformed lymphocytes were employed to enhance the production of antibodies and to detect the clones from peripheral blood lymphocytes. Peripheral blood lymphocytes were obtained from 40 islet cell antibody-negative Type 1 diabetic patients, 10 antibody-positive Type 1 diabetic patients, 30 Type 2 (non-insulin-dependent) diabetic patients and 40 normal control subjects. Epstein-Barr virus-transformed lymphocytes were cultured for 4 weeks and the culture supernatants were used for assay of islet cell antibodies. Islet cell antibody assays were performed by immunohistochemical methods using peroxidase-labelled protein A for IgG antibodies, peroxidase-labelled anti-human IgM antibodies for IgM antibodies and fresh frozen human pancreatic tissue. IgG-islet cell antibodies were detected in 26 islet cell antibody-negative patients (65%), eight antibody-positive patients (80%) and one Type 2 diabetic patient (3%) in the culture supernatants. Islet cell antibodies in the supernatants could not be detected in any of the control subjects. IgM-islet cell antibodies could not be detected in any of the patients or control subjects.(ABSTRACT TRUNCATED AT 250 WORDS)

Autoantibodies↗

PubMed1991

Quantitative structure-activity studies on indole alkaloid tumor promoter indolactam congeners.

Nine indolactam congeners with L-Abu, gamma,delta-delta-Nva, Nva, Phg, tert-Leu, Leu, Ile, allo-Ile, Nle, instead of L-Val in (--)-indolactam-Val, were synthesized by microbial conversion and examined using two biological tests related to tumor promotion. The tests were inhibition of the specific binding of [3H]12-O-tetradecanoylphorbol-13-acetate (TPA) to the mouse epidermal particulate fraction, and stimulation of radioactive inorganic phosphate incorporation into phospholipids of HeLa cells. These two biological activities correlated well for each derivative. (--)-Indolactam-Ile with L-Ile in place of L-Val in (--)-indolactam-Val, which we have recently confirmed to occur naturally, was the most active of the ten indolactam congeners tested, suggesting that (--)-indolactam-Ile is a more potent tumor promoter than (--)-indolactam-Val in vivo. The effects of the substituents at position 12 on the TPA receptor binding were analyzed quantitatively using physicochemical substituent parameters and regression analysis. The results indicated that both hydrophobicity and bulkiness of the substituents at position 12 increased the binding ability to the TPA receptor, supporting the recent hypothesis that the isopropyl group at position 12 of (--)-indolactam-Val is involved in the hydrophobic interaction on the receptor site.

Alkaloids↗