Regulation of the ghrelin gene: growth hormone-releasing hormone upregulates ghrelin mRNA in the pituitary

Ghrelin, an endogenous ligand for the growth hormone secretagogue receptor (GHS-R), was originally purified from the rat stomach. Ghrelin specifically releases GH following intravenous administration, and its GH-releasing activity in vivo is dependent on growth hormone-releasing hormone (GHRH). We previously reported that the expression of the GHS-R gene in the pituitary is developmentally regulated and GHRH infusion increases pituitary levels of GHS-R mRNA. Ghrelin mRNA and peptide have recently been detected in rat and human pituitaries. However, the regulation of the ghrelin gene in the pituitary is unknown. In this study, pituitary levels of ghrelin mRNA were measured with the reverse transcriptase-polymerase chain reaction in male rats at embryonic day (e)18 and postnatal days 1, 10, 30, and 75. The highest concentrations of ghrelin mRNA in the pituitary were observed at e18 and then they declined with age. The infusion of GHRH (10 microg/h, 4h) in freely-moving adult male rats resulted in a 1.9-fold increase in ghrelin mRNA levels relative to control rats (P < 0.05). These data indicated that the expression of the ghrelin gene in the pituitary is developmentally regulated and the pituitary ghrelin/GHS-R signaling system could modulate the regulation of GH secretion by GHRH.

[A case of elderly onset Parkinson's disease complicated by dropped head syndrome]

An 86-year old man presented with a 7-year history of gait disturbance. He was admitted to our hospital on April 2000 because he was experiencing difficulty eating due to progression of dropped head syndrome. Upon standing and sitting, remarkable dropped head and kyphosis were observed. When lying, the patient was able to stretch his neck, and he could stand and walk with the aid of a walker. Rigidity and resting tremor were present predominantly in the lower limbs. Parkinson's disease was diagnosed therefore L-dopa and Cabergoline were administered. Parkinsonism and dropped head syndrome improved in response to treatment. Cases involving dropped head syndrome due to Parkinson's disease are reportedly improved by L-dopa, but exasperated by dopamine agonists. The mechanism of dropped head is thought to be an imbalance in the tonus of the anterior and posterior neck muscles. Dropped head in the present case may have been a complication of Parkinson's disease since it improved in response to L-dopa.

Estimation of coronary flow reserve with the use of dynamic planar and SPECT images of Tc-99m tetrofosmin

BACKGROUND

We developed a noninvasive method to examine coronary flow reserve with technetium 99m tetrofosmin based on the microsphere model. According to the microsphere model, myocardial blood flow (MBF) can be calculated by MBF = q / integral C(t)dt, where q is myocardial activity and C(t) is tracer concentration in blood. Because the ratio of integral C(t)dt at stress to rest is equal to the ratio of the first transit count in the pulmonary artery (PA) and attenuation factors were canceled out, we calculated the increase ratio of MBF (MBF(IR)).

METHODS AND RESULTS

After injection of dipyridamole, tetrofosmin was injected as a bolus and serial dynamic planar images were obtained to measure the first transit count in PA (PAC). Myocardial single photon emission computed tomography was performed to measure the regional myocardial count (RMC). MBF(IR) was calculated as [(RMCs x PACr)/(RMCr x PACs) - 1] x 100, where r and s denote resting and stress conditions, respectively. In contrast, the increase in the myocardial uptake ratio (MUR(IR)) was defined as (RMCs x SCr/RMCr x SCs - 1) x 100, where SC is syringe count of tracer. The results were as follows: (1) The mean MBF of healthy subjects was 46.9% +/- 22.8%. (2) MBF(IR) of the infarcted region and ischemic region was significantly decreased (8.3% +/- 12.2% and 11.2% +/- 11.9%, respectively; P <.001). (3) MUR(IR) was significantly lower than MBF(IR) (14.1% +/- 21.2%; P <.001). (4) MBF(IR) decreased according to the heart rate at rest (r = 0.47; P <.05).

CONCLUSIONS

MBF(IR) is a potential parameter with which to evaluate coronary flow reserve when the changes of arterial input function during stress are considered.

Dynamic changes in cardiac fatty acid metabolism in the stunned human myocardium

BACKGROUND

The chronological changes or mechanisms in cardiac fatty acid metabolism under clinical conditions of hypoxia and ischemia have not been fully elucidated. 123-15-(p-iodophenyl)-3-R,S-methylpentadecanoic acid (BMIPP) can be used with single photon emission computed tomography (SPECT) to evaluate myocardial fatty acid metabolism. We investigated chronological changes in energy metabolism in the stunned human myocardium by means of 123I-BMIPP myocardial SPECT.

METHODS AND RESULTS

We conducted 123I-BMIPP myocardial SPECT in 10 patients with stunned myocardium during the acute, subacute and chronic phases after onset. The left ventricle was divided into 9 regions on SPECT, and the degree of abnormalities in each region was scored in four grades from normal (0) to defect (4). We also examined wash-out rates on BMIPP images. The scores on early BMIPP images in the acute, subacute and chronic phases were 5.6 +/- 1.8, 13.4 +/- 3.5 and 2.5 +/- 1.1, respectively, and the score was highest in the subacute phase (p < 0.001). Similarly, scores on the late images were 2.3 +/- 1.7, 18.3 +/- 4.5 and 4.7 +/- 2.6, respectively, and highest in the subacute phase (p < 0.001). The wash-out rates (normal: 18.2 +/- 2.1%) in the acute, subacute and chronic phases were 12.1 +/- 4.8%, 44.9 +/- 10.0% and 23.1 +/- 4.6%, respectively, with the value being lowest during the acute phase (p < 0.05), and highest during the subacute phase (p < 0.001).

CONCLUSION

These results suggested that fatty acid metabolism in the stunned human myocardium changes dynamically over time.

Morphogenesis of MDCK cells in a collagen gel matrix culture under stromal adipocyte-epithelial cell interaction

BACKGROUND

The stromal-epithelial cell interaction is essential for epithelial morphogenesis. Recently, the specific stromal cell type adipocytes, which abundantly exist in perirenal adipose tissue, have been suggested to affect the biological behavior of some epithelial cell types. However, adipocyte-renal epithelial cell interaction remains unclear. We thus examined the effects of adipocytes on the morphogenesis of renal epithelial cells.

METHODS

The renal epithelial cell line, Madin-Darby canine kidney (MDCK), cells were cultured in three-dimensional collagen gel matrix with or without mature unilocular adipocytes. Cultures cells were examined by histochemistry, immunohistochemistry, and electron microscopy.

RESULTS

Adipocytes extensively promoted the tubule formation of MDCK cells in two different manners. In the first type, after approximately 20% of MDCK cells actively adhered to adipocytes; they organized double-cell structured tubules between the adipocytes and the gel, contacting directly with the entire surface of the adipocytes. In the second type, approximately 70% of MDCK cells apart from adipocytes also formed tubules that had no contact with adipocytes. The component cells of both tubule types at the apical side showed microvilli and peanut agglutinin lectin-positive stain. These cells at the basal side had the basal lamina and type IV collagen-positive stain.

CONCLUSIONS

These results indicate that the specific stromal cell type adipocytes cause MDCK cells to organize the well-polarized tubular structures in two different manners according to their direct and indirect interactions, suggesting that adipocytes may be involved in the regulatory mechanism of renal epithelial morphogenesis.

Subcutaneous adipocytes promote the differentiation of squamous cell carcinoma cell line (DJM-1) in collagen gel matrix culture

Cancer cell-stromal cell interaction plays a crucial role in the malignant growth of cancer cells. In the skin, the main stromal cell types consist of dermal fibroblasts and subcutaneous adipocytes. Fibroblasts are shown to promote the invasive growth of various cancer cell types. The interaction between cancer cells and stromal adipocytes, however, has not been sufficiently studied even in cutaneous carcinoma. To address the effects of adipocytes on the biologic behavior of cancer cells, we examined the growth and differentiation of a squamous cell carcinoma cell line of the skin (DJM-1), using a three-dimensional collagen gel matrix culture with a cutaneous environmental factor, air exposure. The growth was estimated by the uptake of bromodeoxy-uridine (BrdU) for 24 h. The BrdU indices of DJM-1 cells in stromal-cell-free, fibroblast-containing, and adipocyte- containing conditions were 19.7 +/- 1.9%, 19.8 +/- 2.8%, and 4.7 +/- 1.4%, respectively, whereas the BrdU index on the gel containing both fibroblasts and adipocytes was 10.4 +/- 3.3%. In terms of differentiation, DJM-1 cells cocultured with adipocytes constructed the best-organized stratified layer with a cornified-like structure in all conditions above. The differentiation markers involucrin and cytokeratin 10 were immunohistochemically detected in this structure of DJM-1 cells. Adipocyte-induced phenomena were not affected distinctively by air exposure. These results indicate that adipocytes, but not fibroblasts, promote the differentiation of squamous cell carcinoma cells (DJM-1) and inhibit their growth. These adipocyte-induced phenomena were not completely inhibited by fibroblasts. In conclusion, we suggest that stromal adipocytes may be involved in the differentiating mechanisms of cutaneous carcinoma cells.

Assessment of ampulla (Takotsubo) cardiomyopathy with coronary angiography, two-dimensional echocardiography and 99mTc-tetrofosmin myocardial single photon emission computed tomography

We studied the causative mechanism of ampulla (Takotsubo) cardiomyopathy.

METHODS

We examined 7 patients with ampulla cardiomyopathy by means of coronary angiography, two-dimensional echocardiography and 99Tc-tetrofosmin myocardial SPECT at the time of emergency admission (acute phase), at 3 to 5 days after the attack (subacute phase) and at 1 month after the attack (chronic phase). The left ventricle was divided into 9 regions on two-dimensional echocardiograms and 99mTc-tetrofosmin myocardial SPECT images, then the degree of abnormalities in each region was scored in four grades from normal (0) to severely abnormal (3). We injected nicorandil into the coronary arteries and determined the elevation in the ST segment before and after administration.

RESULTS

Coronary angiography did not show stenotic lesions in any patient. The acute, subacute and chronic phase myocardial perfusion scores on 99mTc-tetrofosmin myocardial SPECT were 11.2 +/- 3.4, 2.7 +/- 2.3 and 0.4 +/- 0.5, respectively, and wall motion scores on echocardiograms were 13.0 +/- 3.6, 4.4 +/- 2.2 and 0.6 +/- 0.6, respectively, indicating improvement in all scores during the subacute phase (p < 0.01). The elevation in the ST segment (mm) on the electrocardiogram was improved from 8.3 +/- 2.7 to 4.9 +/- 1.9 after the administration of nicorandil (p < 0.05).

CONCLUSION

These findings indicated that coronary microvascular spasm is one causative mechanism of ampulla cardiomyopathy.

Cellular integration of thyrocytes and thyroid folliculogenesis: a perspective for thyroid tissue regeneration and engineering

Thyroid gland is composed of many spheroid structures called thyroid follicles, in which thyrocytes are integrated in their specific structural and functional polarization. In conventional monolayer and floating cultures, the cells cannot reorganize follicle structures with normal polarity. By contrast, in a 3-D collagen gel culture thyrocytes easily and stably reconstruct follicles with physiological polarity. Integration of thyrocyte growth and differentiation appears to result in eventual thyroid folliculogenesis. 3-D collagen gel culture and subacute thyroiditis, a specific thyroid disorder, are the promising models for addressing the mechanism of thyroid folliculogenesis. Because formation of 3-D follicles actively occurs both in this culture system and at the regenerative stage of the disease. The understanding of the mechanistic basis of folliculogenesis is prerequisite for establishment of an artificial thyroid tissue, which would enable a more physiological approach to the treatment of hypothyroidism caused by various diseases and surgical processes than conventional hormone replacement therapy. In this review, we have discussed thyrocyte integration, and thyroid folliculogenesis and tissue regeneration, to further thyroid biology. Also, we briefly discussed a perspective on thyroid tissue regeneration and engineering.

[Assessment of myocardial damage and metabolic disorder in the left ventricle in patients with mitral stenosis using 201Tl and 123I-BMIPP myocardial SPECT]

This study was designed to evaluate the myocardial damage and metabolic disorder of the left ventricle in patients with mitral stenosis. We studied 15 patients with mitral stenosis. Their grade of chronic heart failure using New York Heart Association classification were class I: 5 patients, class II: 5, class III: 3, class IV: 2, respectively. The severely stenotic group (valve area < 1.5 cm2) included 6 patients, mildly stenotic group (1.5 cm2 < or = valve area < 2.5 cm2) included 9. A 111 MBq of 123I-BMIPP was intravenously injected at rest, SPECT images were obtained at 15 min and 3 hours after injection. A 111 MBq of 201Tl was intravenously injected at rest, and SPECT images were obtained at 15 min after injection. Washout rate (WR) of 123I-BMIPP from the whole left ventricle was obtained using polar maps. The concentration of norepinephrine (NE: pg/ml) in the blood at rest was measured. The mean values of pulmonary artery pressure was measured in ten patients using Swan-Ganz catheter. 123I-BMIPP myocardial SPECT and measurement of NE were reexamined in 5 patients after mitral valvuloplasty. NE values were 476 +/- 72 and 793 +/- 286 in classes I + II and III + IV, respectively. NE values was increased in the severe heart failure group (p < 0.05). NE values were 480 +/- 69 and 743 +/- 295 in the mildly and severely stenotic groups, respectively. NE value was increased in severely stenotic group (p < 0.05). Twelve patients showed normal uptake on both 201Tl and 123I-BMIPP myocardial SPECT. Three patients showed slightly reduced uptake on both 201Tl and 123I-BMIPP myocardial SPECT. WR was 27.2 +/- 4.8% and 44.3 +/- 6.7% in class I + II and class III + IV, respectively. WR was increased in severe heart failure group (p < 0.05). WR was 27.8 +/- 6.0% and 41.3 +/- 9.4% in the mildly and severely stenotic group, respectively. WR was increased in the severely stenotic group (p < 0.05). NE was correlated with WR (p < 0.001). In patients with mitral valvuloplasty, WR was 44.3 +/- 6.7% and 31.4 +/- 4.7% before and after mitral valvuloplasty, respectively. NE values were 857 +/- 266 and 574 +/- 165, respectively. Both WR and NE were decreased after mitral valvuloplasty (p < 0.01). In patients with mitral stenosis, WR was increased in the severe heart failure group and severely stenotic group without apparent myocardial damage. Myocardial metabolism in the left ventricle might be influenced by right heart failure through, for example, NE and neurohormonal factors.

A patient with type I CD36 deficiency whose myocardium accumulated 123I-BMIPP after 4 years

A 73-year-old man with aortic regurgitation was examined by 123I-alpha-methyl-p-iodophenylpentadecanoic acid (BMIPP) myocardial single photon emission computed tomography (SPECT) in 1995. Myocardial accumulation was not evident on either the early or the delayed image obtained 15 minutes and 3 hours, respectively, after injecting 123I-BMIPP. Flow cytometric analysis of CD36 expression in monocytes and platelets identified a type I CD36 deficiency. The patient was hospitalized for severe heart failure in 1999. Upon admission, the cardiothoracic ratio on chest X-rays was 73%, and the left ventricular end-diastolic diameter on echocardiograms was enlarged to 77 mm. On the second day, we performed 123I-BMIPP myocardial SPECT. Myocardial accumulation was evident in the delayed, but not in the early image. We repeated 123I-BMIPP myocardial SPECT on the 10th day after admission. Myocardial accumulation was evident on both early and delayed images. 99mTc-tetrofosmin myocardial SPECT was immediately performed after 123I-BMIPP myocardial SPECT to distinguish myocardial from pooling images in the left ventricle, but, because the images from both 99Tc-tetrofosmin and 123I-BMIPP myocardial SPECT were idential, we considered that the 123I-BMIPP myocardial SPECT images reflected the actual myocardial condition. The CD36 molecule transports long-chain fatty acid (LCFA) on the myocardial membrane, but 123I-BMIPP scintigraphy does not show any myocardial accumulation in patients with type I CD36 deficiency, indicating that myocardial LCFA uptake occurs through CD36 on the human myocardial membrane. Even though our patient had type I CD36 deficiency, BMIPP was uptaken by the myocardium during heart failure, suggesting a variant pathway on the human myocardial membrane for LCFA uptake.

Thyrocyte integration, and thyroid folliculogenesis and tissue regeneration: perspective for thyroid tissue engineering

The thyroid gland is composed of many ball-like structures called thyroid follicles, which are supported by the interfollicular extracellular matrix (ECM) and a capillary network. The component thyrocytes are highly integrated in their specific structural and functional polarization. In conventional monolayer and floating culture systems, thyrocytes cannot organize themselves into follicles with normal polarity. In contrast, in 3-D collagen gel culture, thyrocytes easily form stable follicles with physiological polarity. Integration of thyrocyte growth and differentiation results ultimately in thyroid folliculogenesis. This culture method and subacute thyroiditis are two promising models for addressing mechanisms of folliculogenesis, because thyroid-follicle formation actively occurs both in the culture system and at the regenerative phase of the disorder. The understanding of the mechanistic basis of folliculogenesis is prerequisite for generation of artificial thyroid tissue, which would enable a more physiological strategy to the treatment of hypothyroidism caused by various diseases and surgical processes than conventional hormone replacement therapy. We review here thyrocyte integration, and thyroid folliculogenesis and tissue regeneration. We also briefly discuss a perspective for thyroid tissue regeneration and engineering.

Ovarian carcinoma recurring as carcinosarcoma

Malignant mixed mesodermal tumor is a rare tumor of the ovary and its histogenesis is controversial. We report the case of an ovarian tumor that seemed to be a pure carcinoma and recurred as a carcinosarcoma, and suggest a possible histogenesis for this kind of tumor. The patient was a 62-year-old Japanese woman. The primary tumor was confined to the right ovary and was a histologically poorly differentiated endometrioid adenocarcinoma with focal squamous differentiation. The tumor recurred as peritoneal dissemination 9 months later showing a histological appearance of carcinosarcoma of heterologous type. The recurrent tumor also contained intermingled foci of similar histology as the primary tumor. The carcinomatous component of the recurrent tumor showed more obvious differentiation to adenocarcinoma with increased expression of epithelial markers compared to the primary tumor. Epithelial membrane antigen was positive also in a few cells of the sarcomatous component, which implies that this tumor had features of metaplastic carcinoma. The DNA ploidy pattern of the primary ovarian tumor was diploid, while an additional aneuploid subpopulation appeared in the recurrent tumor. These findings suggest the possible histogenesis of carcinosarcoma of the ovary as progression and clonal evolution of endometrioid adenocarcinoma.

Assessment of left ventricular diastolic function from quantitative electrocardiographic-gated 99mTc-tetrofosmin myocardial SPET

We have developed new software which can evaluate left ventricular (LV) diastolic functional parameters from a quantitative gated SPET (QGS) program. To examine its accuracy, we compared these findings with the LV diastolic functional indices obtained from gated radionuclide ventriculography (RNV). Twenty-four patients were selected for this study. Gated SPET with technetium-99m tetrofosmin was performed and the QGS program was used with a temporal resolution of 32 frames per R-R interval. The LV volume of each frame was calculated and four harmonics of Fourier series were retained for the analysis of the LV volume curve. From this fitted curve and its first derivative curve, we derived LV systolic functional indices, e.g. ejection fraction (EF), peak ejection rate (PER) and time to PER (TPER), as well as LV diastolic functional variables, e.g. 1/3 filling fraction (1/3 FF), peak filling rate (PFR) and time to PFR (TPFR). Within 5+/-2 days, gated RNV was performed and diastolic functional parameters were determined by the same method. No significant difference was observed between the variables calculated by gated SPET and by gated RNV. There was a good correlation between EF, PER, TPER, 1/3 FF, PFR and TPFR determined by these two methods (EF: r=0.95, P<0.0001; PER: r=0.87, P<0.0001; TPER: r=0.84, P<0.0001; 1/3 FF: r=0.87, P<0.0001; PFR: r=0.92, P<0.0001; TPFR: r=0.89, P<0.0001). Bland-Altman plots did not reveal any significant degree of directional measurement bias in any of the comparisons of gated SPET data and RNV data. It is concluded that, in addition to the conventional LV systolic functional indices, our program accurately provides LV diastolic functional parameters from gated SPET. Also, this program will be useful for detecting LV diastolic dysfunction in various cardiac diseases before LV systolic dysfunction becomes evident.

Characterization of coagulase from Staphylococcus intermedius

A protein coagulase was isolated from Staphylococcus intermedius 6131 using bovine prothrombin-Sepharose 4B and Bio-gel P-4 column chromatographies. Homogeneity was demonstrated by the formation of a single band in polyacrylamide gel electrophoresis and isoelectric focusing. The purified preparation possesses a molecular weight of 64,500, an isoelectric point of 4.1, consists of 615 total amino acid residues and demonstrates coagulase activity for human and rabbit fibrinogen, but does not show the activity for rat or guinea pig fibrinogens. This purified protein contains galactose and fucose, and the amino-terminal amino acid sequence was determined. The coagulase activity is inhibited by N-bromosuccinimide (NBS), suggesting that tryptophan is involved in this activity. The coagulase was heat stable to 80 degrees C and stable to pH over the range of 7-9. This is the first report of coagulase from Staphylococcus intermedius.

[Unusual changes detected by iodine-123 15-(p-iodophenyl)-3-R,S-methylpentadecanoic acid myocardial single photon emission computed tomography in the process of acute myocardial infarction: a case report]

Iodine-123 15-(p-iodophenyl)-3-R,S-methylpentadecanoic acid myocardial single photon emission computed tomography(iodine-123 BMIPP myocardial SPECT) is useful for the diagnosis and evaluation of ischemic myocardial disease or cardiomyopathy. Changes in fatty acid metabolism in the post-myocardial ischemic state were evaluated using iodine-123 BMIPP myocardial SPECT. A 77-year-old woman was hospitalized for treatment of acute myocardial infarction. Emergency coronary angiography showed severe stenosis with delayed filling of contrast medium in the middle portion of the left anterior descending artery, so primary percutaneous transluminal coronary angioplasty was performed successfully. On the second day, iodine-123 BMIPP uptake was decreased slightly on the early imaging in the apico-anterior region, and increased slightly on the delayed imaging. On the seventh day, iodine-123 BMIPP uptake was decreased moderately or markedly in the apico-anterior region on the early imaging, and decreased markedly on the delayed imaging. Iodine-123 BMIPP myocardial SPECT subsequently became almost normalized. These unusual dynamic changes In iodine-123 BMIPP myocardial SPECT imaging may reflect metabolic changes of fatty acids in the ischemic state, the size of the triacylglycerol pool, and the degree of turnover in the triacylglycerol pool.

Combined effect of extracellular matrices and growth factors on bovine corneal endothelial cells in culture

PURPOSE

First, to confirm that corneal endothelial cells in the confluent state have the capability to form cellular covering. Second, to establish a method to study the combined effect of extracellular matrices (ECMs) and growth factors on the biological response in corneal endothelial cells in culture.

METHODS

Bovine corneal endothelial cells were cultured inside a cylinder set on a plastic dish. They formed a confluent cell nest on the dish coated with type I or type IV collagen, laminin, or fibronectin. After the removal of the cylinder, hepatocyte growth factor (HGF), epidermal growth factor, transforming growth factor-alpha or transforming growth factor-beta(1) was added to the cultures. Each confluent cell nest enlarged outward, and its increased area size was measured. Cellular response in the nest, including cellular proliferation, was analyzed.

RESULTS

The size of the increased area of the culture on type IV collagen plus HGF was the largest of all the combinations of ECMs and growth factors. The responses of component cells in the increased area consisted of cellular hypertrophy, proliferation, migration and giant cell formation. The treatment with type IV collagen plus HGF clearly promoted all the above responses.

CONCLUSIONS

The biological response of corneal endothelial cells was regulated by ECMs and growth factors.

Novel non-peptide GPIIb/IIIa antagonists: synthesis and biological activities of 2-[4-[2-(4-amidinobenzoylamino)-2-(substituted)acetyl]-3-(2-methoxy-2-oxoethyl)-2-oxopiperazinyl] acetic acids

To improve the in vitro and in vivo potency of our first low molecular weight GPIIb/IIIa antagonist 1 (TAK-029), a series of 2-[4-[2-(4-amidinobenzoylamino)-2-(substituted)acetyl]-3-(2-methoxy-2-oxoethyl)-2-oxopiper-azinyllacetic acids were synthesized through modification of the glycine moiety of 1 and evaluated for their ability to inhibit in vitro adenosine 5'-diphosphate (ADP)-induced platelet aggregation of guinea pig platelet rich plasma (PRP). Among the compounds examined, the (3S,2S)-4-methoxyphenylalanine derivative 4h showed the most potent antagonistic activity with an IC50 value of 13 nM. Dose-dependent inhibition of ex vivo platelet aggregation was achieved with oral administration of 4h (0.3-1.0 mg/kg) to guinea pigs. Complete inhibition was observed for up to 8 h, and 43% inhibition could still be observed 24 h after oral administration of 1.0 mg/kg. The long-lasting antiplatelet effect of 4h suggests that 4h would be suitable for once-a-day dosing. Structure-activity relationships (SAR) were examined in the series of the phenylalanine derivatives. An increase in the electron density around the 4-position of the phenyl ring of the phenylalanine moiety led to an increase in the antiplatelet activity, suggesting the existence of a hydrophobic and electrostatic interaction site in addition to the ionic binding sites in the GPIIb/IIIa.

Thyroid hormones regulate pituitary growth hormone secretagogue receptor gene expression

Thyroid hormones regulate growth hormone (GH) secretion by actions both at the hypothalamus and at the pituitary gland. At the level of the pituitary, thyroid hormones increase GH and GH-releasing hormone receptor (GHRH-R) mRNA expression. To test if thyroid hormones might also regulate the pituitary expression of mRNA for the recently identified GH secretagogue (GHS) receptor, GHS-R, primary pituitary cell cultures from adult male rats were treated with triiodothyronine (T3) and GHS-R mRNA levels were assessed by reverse transcriptase-polymerase chain reaction. T3 increased pituitary GHS-R mRNA levels in a dose- and time-dependent manner. The stimulatory action of T3 on GHS-R mRNA levels was also observed in the presence of the RNA synthesis inhibitor, actinomycin D, indicating that gene transcription is not required. Closer examination of the decay rates of GHS-R mRNA in the presence of actinomycin D revealed T3 extended the half-life of the GHS-R mRNA from 8 h (basal) to15 h, demonstrating that T3 increases GHS-R mRNA levels in vitro by increasing message stability.

[Science in diabetes mellitus]

The Citizen Joint Symposium on "Science in Diabetes Mellitus" was held by the Hokkaido Medical Society at Hokkaido University Conference Hall on October 28, 2000. Six speakers, including three medical doctors, a health nurse, a nutritionist and a physical therapist presented the most-update information on diabetes mellitus based on their specialty. The aim of this symposium was to consider how to support the self-management of patients with diabetes mellitus to keep a quality of life.

An adult case of congenital external carotid-jugular arteriovenous fistula with reversible circulatory insufficiency in the cerebellum and lower brain stem

A 27-year-old man with congenital external carotid-jugular arteriovenous fistula presented with a diminished level of consciousness and an ataxic gait. Axial fluid-attenuated inversion-recovery (FLAIR) MR imaging revealed venous congestion, a dilated right jugular vein, and an area of high signal intensity in the brain stem and cerebellum. Angiography showed a dilated right external carotid artery and jugular vein and the presence of a fistula. After coil embolization of the fistula, axial MR FLAIR images showed only a few areas of high signal intensity in the brain stem and cerebellum. The causal factor was venous congestion in the inferior petrosal sinus and basilar plexus due to high blood pressure in the jugular vein. This case is presented for its unusual clinical and radiologic findings.

Estrogen receptor (ER)alpha, but not ERbeta, gene is expressed in growth hormone-releasing hormone neurons of the male rat hypothalamus

GH synthesis and release from pituitary somatotropes is controlled by the opposing actions of the hypothalamic neuropeptides, GH-releasing hormone (GHRH), and somatostatin (SS). There is a striking sex difference in the pattern of GH secretion in rats. Early reports indicate that gonadal steroids have important imprinting effects during the neonatal period. Recently, our laboratory and others have reported that the GH secretory pattern is altered by short-term gonadal steroid treatment in adult rat, suggesting that gonadal steroids are also important determinants of the pattern of GH secretion during adult life. However, the site of action of gonadal steroids in the adult rat hypothalamus is still unknown. In this study, we used in situ hybridization in the adult male rat brain to determine whether GHRH neurons and/or SS neurons coexpress estrogen receptor alpha (ERalpha) and ERss genes. In the medial basal hypothalamus of adult male rat, the ERalpha messenger RNA (mRNA) was located in medial preoptic area (MPA) and arcuate nucleus (ARC), whereas ERss mRNA was detected in MPA, supraoptic nucleus, and paraventricular nucleus. From studies using adjacent sections, the distribution of ERalpha mRNA-containing cells appeared to overlap in part with those of GHRH and SS expressing cells only in the ARC. On the other hand, the distribution of ERss mRNA-containing cells does not appear to overlap with GHRH cells or SS cells. The double label in situ hybridization studies showed that in the ARC, 70% of GHRH neurons contain ERalpha mRNA, whereas less than 5% of SS neurons expressed the ERalpha gene. These results indicated that GHRH neurons are direct target cells for estrogens, and estrogens may act directly on GHRH neurons through ERalpha during adult life to modify GH secretory patterns.

Effects of fat cells on keratinocytes and fibroblasts in a reconstructed rat skin model using collagen gel matrix culture

BACKGROUND

Fat cells (stromal tissue cells), not only have the function of lipid metabolism, but produce various cytokines that exert an influence on other cell types through paracrine or endocrine mechanisms.

OBJECTIVES

To elucidate possible roles of fat cells in the skin, we examined their effects on the biological behaviour of keratinocytes and dermal fibroblasts in culture.

METHODS

In the present study, focusing upon fat cell--keratinocyte or fat cell--dermal fibroblast interactions, we used a reconstructed skin system with rat skin cells in a three-dimensional collagen gel matrix culture.

RESULTS

In this coculture system, fat cells promoted the proliferation and differentiation of keratinocytes. When keratinocytes were seeded directly on the fat cell layer without dermal fibroblasts, they proliferated extensively and formed a thick epidermal layer with a well-differentiated structure. Conversely, fat cells inhibited the proliferation of dermal fibroblasts. These effects of fat cells were presumed to be mediated by cytokines derived from the fat cells.

CONCLUSIONS

The effects of fat cells could not be mimicked by the addition of leptin, tumour necrosis factor-alpha or insulin-like growth factor-II, suggesting that fat cells are mediating these activities via some other cytokines.

Generation of polyclonal antiserum against the growth hormone secretagogue receptor (GHS-R): evidence that the GHS-R exists in the hypothalamus, pituitary and stomach of rats

Growth hormone (GH) secretagogues (GHSs), which stimulate GH secretion, are synthetic compounds that act through the GHS receptor (GHS-R) which has been recently cloned. We raised an antiserum in a rabbit against a synthetic peptide corresponding to amino acid residues 248-260 of the third intracellular loop of the rat GHS-R. A competitive immunoassay showed that the antiserum had a specific affinity for the target peptide. To confirm the specificity of the antiserum, the GHS-R cDNA was stably expressed in COS-7 cells. In Western blot analysis, the band was detected at 44 kDa in the extracts from COS-7 cells expressing GHS-R (COS-7/tf3-2) but not in those from wild-type COS-7 cells. Furthermore, while COS-7/tf3-2 cells were strongly immunostained for GHS-R, no GHS-R-like immunoreactivity was observed in wild-type COS-7 cells. Immunoreactive bands were also observed at approximately 46 kDa in the extracts from rat hypothalamus, pituitary and stomach by Western blot analysis. These studies are the first to show the existence of GHS-R protein in the stomach. The antiserum for the GHS-R is sensitive and specific, and it would be useful for clarifying the roles of GHS/ghrelin.