Carbonic anhydrase 8 (CAR8) negatively regulates GLP-1 secretion from enteroendocrine cells in response to long-chain fatty acids.

Glucagon-like peptide-1 (GLP-1) is an incretin secreted from enteroendocrine preproglucagon (PPG)-expressing cells (traditionally known as L cells) in response to luminal nutrients that potentiates insulin secretion. Augmentation of endogenous GLP-1 secretion might well represent a novel therapeutic target for diabetes treatment in addition to the incretin-associated drugs currently in use. In this study, we found that PPG cells substantially express carbonic anhydrase 8 (CAR8), which has been reported to inhibit inositol 1,4,5-trisphosphate (IP3) binding to the IP3 receptor and subsequent Ca2+ efflux from the endoplasmic reticulum in neuronal cells. In vitro experiments using STC-1 cells demonstrated that Car8 knockdown increases long-chain fatty acid (LCFA)-stimulated GLP-1 secretion. This effect was reduced in the presence of phospholipase C (PLC) inhibitor; in addition, Car8 knockdown increased the intracellular Ca2+ elevation caused by α-linolenic acid, indicating that CAR8 exerts its effect on GLP-1 secretion via the PLC/IP3/Ca2+ pathway. Car8wdl null mutant mice showed significant increase in GLP-1 response to oral corn oil administration compared with that in wild-type littermates, with no significant change in intestinal GLP-1 content. These results demonstrate that CAR8 negatively regulates GLP-1 secretion from PPG cells in response to LCFAs, suggesting the possibility of augmentation of postprandial GLP-1 secretion by CAR8 inhibition.NEW & NOTEWORTHY This study focused on the physiological significance of carbonic anhydrase 8 (CAR8) in GLP-1 secretion from enteroendocrine preproglucagon (PPG)-expressing cells. We found an inhibitory role of CAR8 in LCFA-induced GLP-1 secretion in vitro and in vivo, suggesting a novel therapeutic approach to diabetes and obesity through augmentation of postprandial GLP-1 secretion by CAR8 inhibition.

Nutritional status and management of risks due to physical therapy in patients hospitalized for long periods.

[Purpose] This study aimed to understand the nutritional status of patients hospitalized for long periods and the risk of physical therapy (PT) for such patients. [Subjects and Methods] Participants were selected from patients who were hospitalized at a designated medical long-term care sanatorium. The participants were divided into 5 groups (A-E) depending on their mode of energy intake and ambulatory ability during PT. The serum albumin level, energy intake, total daily energy expenditure, and total daily energy expenditure per session of PT (EEPT) were evaluated for each group. [Results] Protein-energy malnutrition was observed in 69.6% of the participants. No significant association was identified between the serum albumin level and body mass index. Energy intake was significantly higher in Groups D and E, whose energy intake was via ingestion, than in Groups A and B, whose intake was via tube feeding. EEPT was highest in patients of Group E who had gait independence different from the ability of those in groups A-D. [Conclusion] The actual energy intake is lower with tube feeding than with ingestion. Risk management and energy intake should be revisited in elderly patients who have been hospitalized for long periods and subsequently obtain gait independence.

"Initial, continuous and intermittent bolus" administration of minimally-diluted blood cardioplegia supplemented with potassium and magnesium for hypertrophied hearts.

BACKGROUND: Hypertrophied hearts are subject to the deleterious effects of intraoperative ischemia-reperfusion, and stable maintenance of myocardial cardioplegic arrest is essential. Continuous cardioplegia infusion appears an ideal modification to overcome this issue, except for a large amount of crystalloid solution infused into the myocardium. We previously introduced "initial, continuous and intermittent bolus" administration of minimally-diluted blood cardioplegia (mini-BCP) supplemented with potassium and magnesium, and this study was designed to elucidate its efficacy in patients with hypertrophied hearts. METHODS: Thirty patients (M:F=17:13, 69.2+/-7.8 years) with left ventricular mass index greater than 150 g/m(2) who underwent aortic valve replacement between 1996 and 2002 were enrolled, and were allocated to one of the two groups. The same infusion protocol was used for both groups as follows: initial and intermittent (every 20 min) BCP was antegradely infused for 2 min at the rate of 200 mL/min, and continuous retrograde BCP flow rate was set at 60-100mL/min. Group C (n=15) received 4:1-diluted BCP modified with Buckberg solution, and Group M (n=15) were given mini-BCP supplemented with potassium (initial/others: 15.4/9.8 mEq/L) and magnesium (initial/others: 6.5/4.0 mEq/L). RESULTS: Stable cardioplegic arrest was maintained in all study patients, and total amount of crystalloid solution as cardioplegia was lesser in Group M (79.4+/-27.5 mL) than in Group C (937.3+/-372. 1mL, p<0.01). Group M showed a higher incidence of spontaneous heartbeat recovery after aortic unclamping (13 versus 6, p<0.05) and a lower incidence of postoperative atrial fibrillation (0 versus 5, p<0.05). Postoperatively, maximum dopamine dose (3.35+/-2.27 microg/kg/min versus 5.49+/-2.30 microg/kg/min, p<0.05) and peak plasma creatine kinase-myocardial band (CK-MB) (21.7+/-7.2 IU/L versus 28.8+/-8.4 IU/L, p<0.05) were lower in Group M. Early postoperative echocardiography revealed a lower incidence of paradoxical ventricular septal motion (M versus C; 3 versus 10, p<0.05) and greater left ventricular ejection fraction (M versus C; 70.7+/-4.0% versus 67.0+/-5.3%, p<0.05) in Group M. CONCLUSIONS: These results suggest that "initial, continuous and intermittent bolus" administration of mini-BCP, supplemented with potassium and magnesium, is a novel modification for patients with hypertrophied hearts in terms of simplifying the maintenance of cardioplegic arrest with beneficial myocardial protective effects.

Sox7 plays crucial roles in parietal endoderm differentiation in F9 embryonal carcinoma cells through regulating Gata-4 and Gata-6 expression.

During early rodent development, the parietal endoderm appears from an inner cell mass and produces large amounts of basement membrane components, such as laminin-1 and collagen IV. To elucidate the regulatory network for gene expression during these procedures, we constructed a series of short interfering RNA expression vectors targeted to various transcription factors, transfected them into F9 embryonal carcinoma cells, and evaluated the effects of the gene silencing on the induction of parietal endoderm differentiation and basement membrane component production by treating F9 cells with all trans-retinoic acid and dibutyryl cyclic AMP. Among the transcription factors tested, silencing of Sox7 or combined silencing of Gata-4 and Gata-6 resulted in suppression of cell shape changes and laminin-1 production, which are the hallmarks of parietal endoderm differentiation. In cells silenced for Sox7, induction of Gata-4 and Gata-6 by retinoic acid and cyclic AMP treatment was inhibited, while induction of Sox7 was not affected in cells silenced for Gata-4 and Gata-6, indicating that Sox7 is an upstream regulatory factor for these Gata factors. Nevertheless, silencing of Sox7 did not totally cancel the action of retinoic acid, since upregulation of coup-tf2, keratin 19, and retinoic acid receptor beta2 was not abolished in Sox7-silenced F9 cells. Although overexpression of Sox7 alone was insufficient to induce parietal endoderm differentiation, overexpression of Gata-4 or Gata-6 in Sox7-silenced F9 cells restored the differentiation into parietal endoderm. Sox7 is therefore required for the induction of Gata-4 and Gata-6, and the interplay among these transcription factors plays a crucial role in parietal endoderm differentiation.

Minimally-diluted blood cardioplegia supplemented with potassium and magnesium for combination of 'initial, continuous and intermittent bolus' administration.

BACKGROUND: The present study was designed to examine the hypothesis that minimally-diluted blood cardioplegia (BCP) supplemented with potassium and magnesium provides superior myocardial protection in comparison with the standard-diluted BCP for a combination of 'initial, continuous, and intermittent bolus' BCP administration. METHODS AND RESULTS: Seventy patients undergoing elective coronary revascularization between 1997 and 2001 (M : F =55:15, mean age 67.6+/-7.5 years) were randomly divided into 2 groups: Group C (n=35) was given the standard 4:1-diluted blood-crystalloid BCP, and Group M (n=35) was given minimally-diluted BCP supplemented with potassium-chloride and magnesium-sulfate. The BCP temperature was maintained at 30 degrees C. Cardioplegic arrest was induced with 2 min of initial antegrade BCP infusion, followed by continuous retrograde BCP infusion. Intermittent antegrade BCP was infused every 30 min for 2 min. The time required for achieving cardioplegic arrest was significantly shorter in Group M (47.5+/-16.3 vs 62.5+/-17.6 s, p<0.0001). The number of patients showing spontaneous heart beat recovery after reperfusion was significantly larger in Group M (28 vs 15, p=0.0029), and the number of patients suffering from atrial fibrillation during the postoperative period was significantly smaller in Group M (n=3 vs 11, p=0.034). Both the postoperative maximum dopamine dose (3.57+/-2.46 vs 5.44+/-2.23 microg/kg per min, p=0.0014) and peak creatine kinase-MB (19.5+/-8.5 vs 25.8+/-11.9 IU/L, p=0.0128) were significantly less in Group M. The number of patients showing paradoxical movement of the ventricular septum in the early postoperative echocardiography was significantly smaller in Group M (9 vs 24, p=0.0007). CONCLUSIONS: These results suggest that 'initial, continuous and intermittent bolus' administration of minimally-diluted BCP supplemented with potassium and magnesium is a reliable and effective technique for intraoperative myocardial protection.

Type 1 iodothyronine deiodinase in the house musk shrew (Suncus murinus, Insectivora: Soricidae): cloning and characterization of complementary DNA, unique tissue distribution and regulation by T(3).

The house musk shrew Suncus murinus (Insectivora: Soricidae) has been reported as having low thyroxine to 3,3'5-triiodothyronine (T(3)) converting activity in liver and kidney homogenates and was assumed to be type 1 iodothyronine deiodinase (D1)-deficient. To study whether this is due to structural abnormality of shrew D1, we cloned the cDNA and characterized the enzyme. The deduced amino acid sequence of shrew D1 was found to be highly homologous to other known D1s and the enzyme itself to have similar catalytic activity. However, unlike in other species, the D1 activity was detected only in liver. Moreover, the D1 activity in liver of the shrew was less than half of that in rat liver and its expression was not up-regulated by T(3). In contrast, a very high activity of D2 was demonstrated in brain and brown adipose tissue. The present study also revealed that the serum level of T(3) in the shrew was in the same range as these in other mammals. These results suggest that D2 contributes to the production and maintenance of T(3) levels in the house musk shrew.

Steroid receptor coactivator-1 deficiency causes variable alterations in the modulation of T(3)-regulated transcription of genes in vivo.

Thyroid hormone exerts its biological effect by binding to a TR. Both liganded and unliganded TRs regulate the transcription of T(3)-responsive genes. Cofactors with activating or repressing function modulate the transcriptional regulation by TRs. We showed that steroid receptor coactivator 1 (SRC-1)-deficient mice (SRC-1(-/-)) exhibit partial resistance to thyroid hormone at the level of the pituitary thyrotrophs. To determine whether SRC-1 deficiency affects globally T(3)-dependent transcriptional regulation, we studied the effects of thyroid hormone deprivation and replacement on the expression of several genes in different tissues of SRC-1(-/-) and wild-type mice (SRC-1(+/+)). Thyroid hormone deficiency was induced by a low iodine diet (LoI) supplemented with propylthiouracil (PTU) for 2 wk. L-T(3) was injected ip for the last 4 d in one group (PTU+T(3) group), and another group (PTU group) received only vehicle. Levels of mRNAs for T(3)-responsive genes were determined by Northern blotting: GH and TSH beta in pituitary; type 1 iodothyronine 5'-deiodinase, spot 14 (S14), and malic enzyme in liver; and sarcoplasmic reticulum calcium adenosine triphosphatase 2 and myosin heavy chain alpha and beta in heart. Serum parameters, TSH, total cholesterol, creatine kinase, and alkaline phosphatase (AP), were also measured. Hypothyroidism produced a comparable increase in TSH beta mRNA in both genotypes, but its suppression by L-T(3) was attenuated in SRC-1(-/-) mice. In contrast, hypothyroidism failed to reduce S14 mRNA levels in SRC-1(-/-) mice. As a consequence, the response to L-T(3) was not observed in these mice. SRC-1 deficiency had no effect on the expression of the rest of the T(3)-responsive genes examined. Of the four serum parameters, the T(3)-mediated decrease in TSH and changes in AP were attenuated in SRC-1(-/-) mice. We conclude that SRC-1 deficiency altered the expression of only some of the T(3)-responsive genes. SRC-1 appears to be involved not only in transcriptional activation by liganded TRs, but also in the suppression by liganded or unliganded TRs. Some of the effects of SRC-1 may be TR isoform specific.