Development of anti-HBV agents targeting HBV capsid proteins.

Hepatitis B is a viral hepatitis, which is caused by infection of hepatitis B virus (HBV). This disease progresses to chronic hepatitis, cirrhosis and liver cancer. To treat hepatitis B, exclusion of virus and covalently closed circular DNA (cccDNA) that is formed in hepatocyte nucleus is necessary. A hepatitis B capsid protein (HBc) is an indispensable protein, which forms the capsid that encapsulates viral DNA. Since HBc is correlated to the transcriptional regulation of cccDNA, this protein would be an attractive target for complete cure of hepatitis B. By in silico screening of a library of compounds, a small compound, Cpd4 (1), which binds to a hydrophobic cavity located in the inner pocket on the tetramer interface of HBc proteins, was identified. In anti-HBV assays, this synthetic compound, Cpd4 (1) decreased the amount of HBV core related antigen (HBcrAg), which has been correlated with the proliferation of HBV, and decreased the amount of HBV surface antigen (HBsAg), which is correlated with the amount of cccDNA. Based on Cpd4 (1) as a lead compound, 20 derivatives of 1 were designed and synthesized and their structure-activity relationships were examined. As a result, specific interactions between each compound and amino acid residues of the target protein appeared to be unimportant but the shape/size of compounds which can bind to the hydrophobic cavity might be important in the expression of high anti-HBV activity, and a more potent derivative, TKB-HBV-CA-001 (3b), was discovered. These results will be useful in the development of novel anti-HBV agents for a complete cure of hepatitis B.

Potent and biostable inhibitors of the main protease of SARS-CoV-2.

Potent and biostable inhibitors of the main protease (Mpro) of SARS-CoV-2 were designed and synthesized based on an active hit compound 5h (2). Our strategy was based not only on the introduction of fluorine atoms into the inhibitor molecule for an increase of binding affinity for the pocket of Mpro and cell membrane permeability but also on the replacement of the digestible amide bond by a surrogate structure to increase the biostability of the compounds. Compound 3 is highly potent and blocks SARS-CoV-2 infection in vitro without a viral breakthrough. The derivatives, which contain a thioamide surrogate in the P2-P1 amide bond of these compounds (2 and 3), showed remarkably preferable pharmacokinetics in mice compared with the corresponding parent compounds. These data show that compounds 3 and its biostable derivative 4 are potential drugs for treating COVID-19 and that replacement of the digestible amide bond by its thioamide surrogate structure is an effective method.

Small-Molecule Anti-HIV-1 Agents Based on HIV-1 Capsid Proteins.

The capsid of human immunodeficiency virus type 1 (HIV-1) is a shell that encloses viral RNA and is highly conserved among many strains of the virus. It forms a conical structure by assembling oligomers of capsid (CA) proteins. CA dysfunction is expected to be an important target of suppression of HIV-1 replication, and it is important to understand a new mechanism that could lead to the CA dysfunction. A drug targeting CA however, has not been developed to date. Hydrophobic interactions between two CA molecules via Trp184/Met185 in CA were recently reported to be important for stabilization of the multimeric structure of CA. In the present study, a small molecule designed by in silico screening as a dipeptide mimic of Trp184 and Met185 in the interaction site, was synthesized and its significant anti-HIV-1 activity was confirmed. Structure activity relationship (SAR) studies of its derivatives were performed and provided results that are expected to be useful in the future design and development of novel anti-HIV agents targeting CA.

Auxiliary liver organ formation by implantation of spleen-encapsulated hepatocytes.

Hepatocyte transplantation is an attractive alternative to orthotopic liver transplantation. However, its application has been limited because of its short-term success only. Here we report a new approach to hepatocyte transplantation resulting in the generation of an auxiliary liver in vivo. Isolated primary hepatocytes were encapsulated in isolated spleens and then transplanted by attaching the spleens to the livers of recipient animals (mice or rats) using biodegradable adhesive. A vascular network was rapidly established, and protein molecules circulated freely between the transplanted spleen and the liver, to which they adhered. In contrast, the spleen, which did not adhere to the liver or adhered elsewhere (adipose tissue or peritoneum), did not become vascularized but shrank and died. Encapsulation of hepatocytes in an isolated spleen enhanced their survival significantly, and co-encapsulation of Engelbreth- Holm-Swarm gel together with the hepatocytes further enhanced it. The encapsulated hepatocytes expressed liver-specific differentiation genes for more than 3 weeks. Plasma albumin concentrations in Nagase analbuminemic rats began to increase 3 days after transplantation. The transplanted hepatic cells migrated into the liver parenchyma, whereas the spleen was absorbed. Thus, we have developed a novel, simple approach for the rapid and efficient formation of functional auxiliary liver using a modified hepatocyte transplantation method.

[An experimental weekly visit of the ward at Higashi Yamato Hospital--a holistic cooperation].

The city of Higashi Yamato is located in the northern part of Tama, Suburbs of Tokyo, and the population of Higashi Yamato is approximately 80,000. The Higashi Yamato visiting nursing station was opened in April 1998. As of April 2006, we have over 100 patients, and the aggregate visiting nursing services have provided more than 600 cases. Our station's uniqueness is that forty percent of the patients have malignant neurological disorders and are terminal stage patients, and that they are all covered by medical care insurance. We also provide nursing services to patients who are expected to be dying peacefully at home averaging 4 patients per month. Higashi Yamato Hospital, attached to the visiting nursing station, is an acute phase hospital and has 274 beds. The average hospital stay for our patients was 13 days in 2005. We promote an early discharge from the hospital for patients who have a high need of medical and nursing care and for the patients who are at the terminal stage. However, there were many cases where visiting nursing care services were provided because of a local care manager's request rather than a visiting nursing care need for patients who will be discharged soon from the hospital and for those expecting to have the service. In reality, we have observed a family being felt that his or her patient was pushed out from the hospital, a family who has no confidence in taking a nursing task at home, and a family who could not cope with the patient's changing condition. Therefore, we wanted resolve these observed problems urgently to create close cooperation with the hospital in order to provide continued nursing care after a patient is discharged from the hospital and to have home medical care safely. As a result, we planned a visit to the ward on a weekly basis starting on February 2006. We report here because we had a good result.

[Macular thickness after cataract surgery in diabetic patients].

PURPOSE: Macular edema after cataract surgery is the main cause of unfavorable visual outcome and more common in diabetic patients. The objective of this study was to evaluate the time course of change in macular thickness in diabetic patients, compared with that in nondiabetic patients after uneventful cataract surgery. SUBJECTS AND METHODS: We examined 36 diabetic eyes and 30 nondiabetic controls preoperatively and 1, 3, 7, 30, 90, and 180 days postoperatively, using a Retinal Thickness Analyzer (RTA). Aqueous flare intensity and visual acuity were also measured. RESULTS: Macular thickening and an increase in aqueous flare were marked in diabetic eyes and controls on the first postoperative day. In nondiabetic patients, these subtle changes improved gradually and returned to near-normal within 6 months. In diabetic patients, prolonged and progressive macular thickening was observed 6 months after surgery. Macular edema in diabetic patients had a propensity to cause poorer 6-month visual acuity. CONCLUSIONS: RTA is useful for early detection of macular edema. Using RTA, we demonstrated that cataract surgery induced subclinical macular edema even in nondiabetic subjects and that progressive macular edema might cause poor visual outcome in diabetic patients.