ATP-sensitive K+ channels in the hypothalamus are essential for the maintenance of glucose homeostasis

Glucose-responsive (GR) neurons in the hypothalamus are thought to be critical in glucose homeostasis, but it is not known how they function in this context. Kir6.2 is the pore-forming subunit of K(ATP) channels in many cell types, including pancreatic beta-cells and heart. Here we show the complete absence of both functional ATP-sensitive K+ (K(ATP)) channels and glucose responsiveness in the neurons of the ventromedial hypothalamus (VMH) in Kir6.2-/- mice. Although pancreatic alpha-cells were functional in Kir6.2-/-, the mice exhibited a severe defect in glucagon secretion in response to systemic hypoglycemia. In addition, they showed a complete loss of glucagon secretion, together with reduced food intake in response to neuroglycopenia. Thus, our results demonstrate that KATP channels are important in glucose sensing in VMH GR neurons, and are essential for the maintenance of glucose homeostasis.     

TCR repertoire in early fetal mouse thymus

We investigated the rearrangement and expression of TCR genesin mouse fetal thymus organ culture, a system that avoids subsequententry of hematopoietic precursor cells. The first observablerearranged TCR gene was homogeneous V2-J2, detectable as earlyas fetal day 11 (d11) in the thymic primordla. The productiveTCR was homogeneous V5-J1, first detectable in d13 thymocytes,followed by adult-type TCR (V4 and V7). Sequence analysis ofTCR revealed five types of V-J junctional sequences. In thevery early stage, a homogeneous V-J junction is generated viaa short homology sequence in the coding region (Type I), whilea short homology sequence in the P-nucleotlde rather than thecoding region is used in the following stage (Type II). In thelater embryonic stages, diverse V-J junctions are generatedby well-known mechanisms, such as P-nucleotide (Type III), N-regioninsertion (Type IV) or trimming of the coding ends (Type V).These findings suggest that the generation of homogeneous TCR (V2 and V5) in the early fetal stages is due to the intrinsicrearrangement mechanisms and is in stage specific manner.     

Primary pulmonary low-grade marginal zone B-cell lymphoma of mucosa-associated lymphoid tissue type with prominent hyalinosis. A case report

We report a case of primary pulmonary low-grade marginal zone B-cell lymphoma of the mucosa-associated lymphoid tissue (MALT)-type with prominent sclerosis, which morphologically resembled pulmonary hyalinizing granuloma (PHG) or inflammatory pseudotumor (IPT) of the lung. The patient, a 66-year-old Japanese female with a history of Sj?gren's syndrome and primary biliary cirrhosis, presented with a lower left lobe mass 6.8 cm in diameter. Histologically, the lesion is characterized by dense bundles of collagen with scattered plasma cells, mature small lymphocytes, and histiocytes among the collagen bundles. Only the peripheral area of the nodule contained dense lymphoplasmacytoid and histiocytoid infiltrates. A few centrocyte-like cells were obscured by the numerous plasma cells and plasmacytoid cells. In addition, lymphoepithelial lesions and colonalized lymphoid follicles were identified by immunohistochemistry alone. Although PHG and IPT are unlikely to be confused with pulmonary MALT-type lymphomas, the present case suggests that MALT-type lymphoma should be added to the list of differential diagnoses for PHG and IPT.     

Enhancement of lipopolysaccharide-stimulated cyclooxygenase-2 mRNA expression and prostaglandin E2 production in gingival fibroblasts from individuals with Down syndrome

It is well known that Down syndrome (DS) is a premature ageing syndrome. Periodontal disease in individuals with DS develops rapidly and extensively in a relatively younger age bracket compared with that in healthy controls. The mechanisms involved in the periodontal inflammatory processes in DS patients are not fully understood. In the present study, the non-inflamed gingival fibroblasts isolated from seven patients with DS (DGF) and seven healthy controls (NDGF) were stimulated with lipopolysaccharide (LPS) derived from Actinobacillus actinomycetemcomitans (A. a.). We measured the level of prostaglandin E2 (PGE2) production by DGF and NDGF by radioimmunoassay, and also measured the mRNA expression of cyclooxygenase-1 (COX-1) and cyclooxygenase-2 (COX-2) by using the real-time PCR method. We found the higher levels of LPS-stimulated COX-2 mRNA expression and PGE2 production in DGF when compared with those in NDGF. This study may indicate that overexpression of LPS-stimulated COX-2 induced a greater ability of DGF to produce PGE2, and that these phenomena may be responsible for the severer periodontal disease in DS patients.     

FLORID DUCT LESIONS AND EXTENSIVE BILE DUCT LOSS OF THE INTRAHEPATIC BILIARY TREE IN CHRONIC LIVER DISEASES OTHER THAN PRIMARY BILIARY CIRRHOSIS

Intrahepatic biliary tree with either florid duct lesions or a moderate to severe degree of the duct loss in four livers with chronic hepatic diseases other than primary biliary cirrhosis were studied with histometric and serial section observations. Florid duct lesions, distributed segmentally in the liver, were found in one case with incomplete septal cirrhosis and one case with idiopathic portal hypertension. The florid duct lesions including marked plasma cell infiltration and occasional periductal granulomas, were not associated with any bile duct loss in the two cases. The duct lesions were reversible in one case during a long clinical course. On the other hand, a moderate to severe bile duct loss with biliary epithelial degeneration and necrosis was associated with no or little periductal inflammatory cell infiltration in one other case with chronic intrahepatic cholestasis, probably drug-induced, and in one case with idiopathic portal hypertension. Although florid duct lesions and bile duct loss were important diagnostic features of primary biliary cirrhosis, one of them was observed to develop independently in severely diseased livers, not consistent with a diagnosis of primary biliary cirrhosis, sclerosing cholangitis or intrahepatic bile duct paucity syndrome.     

Effects of ruthenium red on membrane ionic currents in urinary bladder smooth muscle cells of the guinea-pig

 Three major ionic currents, Ca²⁺-dependent K⁺ current (I _K-Ca), delayed rectifier type K⁺ current (I _kd) and Ca²⁺ current (I _Ca), were activated by depolarization under whole-cell clamp in single smooth muscle cells isolated from guinea-pig urinary bladder. Externally applied ruthenium red (RuR) reduced the amplitude of I _K-Ca and I _Ca at 0 mV (IC₅₀ values were 4.2 and 5.6 μM, respectively), but did not affect I _Kd. Spontaneous transient outward currents (STOCs) and caffeine-induced outward currents (I _caf) at –30 mV were reduced by external 10 μM RuR. When 10 μM RuR was added to the pipette solution, I _K-Ca during depolarization, STOCs and I _caf significantly decreased with time. RuR did not change the unitary current amplitude of the large-conductance Ca²⁺-dependent K⁺ (BK) channels, but reduced the open probability of the channel under excised patch-clamp recording mode. RuR reduced the channel activity more effectively from the cytosolic face than from the other. This inhibition decreased when the cytosolic Ca²⁺ concentration was increased. These results indicate that RuR blocks BK and Ca²⁺ channels in urinary bladder smooth muscle cells. The decrease in I _K-Ca, STOCs and I _caf by RuR is attributable to the direct inhibition of BK channel activity, probably in addition to the inhibition of Ca²⁺ release from storage sites. The direct inhibition of BK channel activity by RuR may be related to the interaction of RuR with the Ca²⁺-binding sites of the channel protein. Received: 15 October 1997 / Received after revision and accepted: 25 November 1997     

Lamivudine and IFN-beta sequential therapy in HBe antigen-positive patients with chronic hepatitis B virus genotype C infection.

Sequential treatment with lamivudine and interferon (IFN) has induced sustained biochemical and virologic responses in the majority of patients with chronic hepatitis B in France. However, the efficacy of sequential treatment in patients with chronic hepatitis B virus (HBV) genotype C infection has not been evaluated. Twenty-four HBe antigen-positive patients were treated with 100 mg lamivudine alone for 16-32 weeks, then with both 6 MU IFN-beta and lamivudine for 4 weeks, and lastly with IFN-beta alone for 20 weeks. Sustained response was achieved in 7 (29%) patients 24 weeks after the end of therapy. No lamivudine-resistant variants emerged in any patient. Hepatitis flare occurred in 3 patients after the withdrawal of lamivudine, but none had decompensation. The patients with sustained response were significantly younger at baseline (p = 0.033) and had a significantly lower HBV DNA level at the start of IFN (p = 0.020) than those without sustained response. In conclusion, the rate of response to sequential therapy with lamivudine and IFN in HBe antigen-positive patients with HBV genotype C infection was lower than the rate reported previously. Patients who were young or who had a favorable virologic response to lamivudine were more likely to have a sustained response.     

Reduction of enzymatic activity of tyrosine hydroxylase by a heterocyclic amine, 3-amino-1,4-dimethyl-5H-pyrido(4,3-b)indole (Trp-P-1), was due to reduced affinity to a cofactor biopterin.

A carcinogenic, food-derived heterocyclic amine, 3-amino-1,4-dimethyl-5H-pyrido(4,3-b)indole (Trp-P-1) was found to reduce the enzymatic activity of tyrosine hydroxylase in clonal rat pheochromocytoma PC12h cells, by its supplement to the culture medium. The reduction was observed with 10 microM Trp-P-1, and at this concentration the amount of cell protein and the activity of a non-specific enzyme, beta-galactosidase, were not affected. The mechanism of the reduction of the enzyme activity was clarified by kinetical studies. The amine reduced the affinity of tyrosine hydroxylase to a cofactor, tetrahydrobiopterin. The alteration of the enzymatic properties by Trp-P-1 was discussed in relation to the possible effect on catecholamine metabolism in the brain.     

Hyperplastic epithelial foci in honeycomb lesions in idiopathic pulmonary fibrosis

Seventy-two cases of idiopathic pulmonary fibrosis (IPF) were examined from 2856 consecutive autopsy cases at the Japanese Red Cross Medical Center in Tokyo from 1973-1996. Primary lung cancer had arisen in 31 of 72 cases of IPF (43%), significantly higher than the incidence in cases without IPF (8.1%) and in the cases with non-IPF chronic lung diseases (11.9%). Hyperplastic epithelial foci in the honeycomb lesions of IPF cases were significantly more prominent in the lower than in the upper lobe, in cases with or without lung cancer, and they were more prominent in the lower lobe of IPF with than in those without cancer. The length of hyperplastic epithelial foci in the lower lobe of IPF cases was longer than that in interstitial pneumonia-associated with collagen vascular diseases. There was a higher PCNA labeling index of hyperplastic epithelial foci in IPF cases than in cases of interstitial pneumonia-associated with collagen vascular diseases. The PCNA labeling index was almost the same between smokers and nonsmokers with IPF. Overexpression of p53 was observed in hyperplastic epithelial foci in honeycomb lesion of IPF. DNA ploidy analysis of hyperplastic epithelial foci in the paraffin sections of 12 IPF cases revealed aneuploidy patterns in eight cases. These results strongly suggest that accelerated cell proliferation occurs in the honeycomb lesion of IPF, and that regenerative epithelia becomes susceptible to carcinogenic agents in addition to the smoking effect.