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Biomedical subjects

Yugo Shibagaki

Publications and source records attributed to Yugo Shibagaki.

11 recordsLinked to original sources
PubMed2006

Novel compound heterozygote mutations (H234Q/R1206X) of the ADAMTS13 gene in an adult patient with Upshaw-Schulman syndrome showing predominant episodes of repeated acute renal failure.

BACKGROUND: Unlike acquired thrombotic thrombocytopenic purpura or haemolytic uraemic syndrome, which are often intractable, thrombotic microangiopathy in patients with Upshaw-Schulman syndrome (USS)--a congenital deficiency of von Willebrand factor-cleaving protease (ADAMTS13) activity--responds very well to plasma infusion and does not even require plasma exchange. However, the symptoms significantly vary in each individual and thus clinicians often overlook this diagnosis. METHODS: A 31-year-old adult male patient with thrombotic microangiopathy, which was complicated with repeated episodes of acute renal failure, is reported. We suspected that the patient had USS and performed assays of ADAMT13 activity and its inhibitor, followed by ADAMTS13 gene analysis of the patient and his parents. RESULTS: The patient had extremely low ADAMTS13 activity and has no inhibitors of ADAMTS13. Through an ADAMTS13 gene analysis of this family, we found two novel mutations responsible for the disease: a missense mutation in exon 7 [702 C --> A (H234Q)] from the father and a nonsense mutation in exon 26 [3616 C --> T (R1206X)] from the mother. CONCLUSIONS: Our experience appears to indicate the importance of assays of ADAMTS13 activity and its inhibitor in patients who have episodes of renal insufficiency in association with thrombotic microangiopathy, for diagnosis and choice of treatment.

ADAM Proteins↗
PubMed2005

Thrombotic microangiopathy in malignant hypertension and hemolytic uremic syndrome (HUS)/ thrombotic thrombocytopenic purpura (TTP): can we differentiate one from the other?

Patients with malignant hypertension sometimes exhibit microangiopathic hemolytic anemia/thrombocytopenia known as thrombotic microangiopathy (TMA). On the other hand, severe hypertension is sometimes associated with hemolytic uremic syndrome (HUS)/thrombotic thrombocytopenic purpura (TTP). Because the clinical features of the two entities overlap significantly, it is sometimes difficult to distinguish one from the other. However, such differentiation is indispensable, since early performance of plasmapheresis is critical in HUS/TTP. It has been suggested that severe thrombocytopenia is one of the most useful differential points in diagnosing HUS/TTP from malignant hypertension caused by other etiologies. Early performance of plasmapheresis can be justified in the presence of both TMA and thrombocytopenia. However, thrombocytopenia can be seen in the cases with malignant hypertension from etiologies other than HUS/TTP, and in these particular cases, plasmapheresis is useless and can be harmful. Recently, the plasma level of ADAMTS13 (a disintegrin and metalloprotease domain, with thrombospondin type 1 motif 13), which is a von Willebrand Factor cleaving protease, has been shown to be very low in familial or some of the sporadic cases of TTP, and a low level of ADAMTS13 is very specific to TTP. Some reports have shown that patients with a very low plasma level of ADAMTS13 respond very well to plasmapheresis. We recently experienced two cases with TMA. Although both of our patients had severe hypertension with TMA, different therapeutic strategies ameliorated their illness: symptomatic treatment was effective in case 1, which showed normal ADAMTS13 activity, whereas plasma infusion was necessary to save case 2, which showed low ADAMTS13 activity. Thus, patients with a low level of ADAMTS13 activity might respond well to plasmapheresis or plasma infusion. When presented with patients with severe hypertension and thrombotic microangiopathy, ADAMTS13 activity may prove to be a promising adjunctive tool in differentiating TTP from TMA due to other etiologies, but in the meantime, we should make the choice of whether or not to perform plasmapheresis based on the degree of thrombocytopenia.

ADAM Proteins↗
PubMed2004

Anaemia is common after kidney transplantation, especially among African Americans.

BACKGROUND: Anaemia is a major cardiovascular risk factor in renal disease. It might be appropriate to extrapolate this association of anaemia with cardiovascular disease to renal transplant recipients who continue to have a significant cardiovascular risk. There are very few studies addressing the issue of anaemia after renal transplantation. METHODS: We studied 192 consecutive kidney transplant recipients over a 5-year period in a tertiary referral centre in Michigan, USA. Patients who were followed up at the ambulatory transplant clinic for at least 1 year after transplantation were studied. Haemoglobin (Hb) level at 6 months and 1 year after renal transplantation was recorded. Risk factors for anaemia were evaluated using multivariate regression analysis. RESULTS: Significant anaemia (Hb <11 g/dl in females and <12 g/dl in males) was common (19.3% at 6 months, 19.8% at 1 year). Anaemia was more common in African American (AA) than in non-AA patients both at 6 months and 1 year after transplantation. Multivariate analysis showed that serum creatinine was an independent risk factor for anaemia. Female gender was associated with significant anaemia at 1 year. Intriguingly, AA race was also an independent risk factor at 6 months and strong trend for risk at 1 year. CONCLUSIONS: Anaemia is common during the first year after kidney transplantation. AA race as well as high serum creatinine and female gender are independent risk factors for post-transplant anaemia. The importance of anaemia as a risk factor in AA patients after renal transplantation should be more recognised.

Adolescent↗
PubMed2004

Two cases of renovascular hypertension and ischemic renal dysfunction: reliable choice of examinations and treatments.

We experienced two aged patients with atherosclerotic renovascular stenosis associated with hypertension and ischemic nephropathy. Both patients exhibited sudden rise in blood pressure (BP) and progressive aggravation of renal dysfunction. In these patients, the use of contrast medium to screen for renal artery stenosis (RAS) ran the risk of further deterioration of renal function. We therefore used magnetic resonance angiography (MRA), which is less conducive to renal damage, to screen for RAS. One-sided RAS was treated by percutaneous transluminal angioplasty of the renal artery (PTRA) and stenting. As a result, BP decreased in both patients. Serum creatinine (Cr) decreased slightly in one patient, whereas, in the other, serum Cr increased transiently and then decreased and stabilized to pre-treatment levels. Thus, although it is unclear whether the combination of PTRA and stenting is among the best treatments for patients with RAS and moderate-to-severe renal dysfunction, PTRA and stenting are clearly of benefit in selected patients. In addition, recent progress in characterizing the pathophysiology of ischemic nephropathy associated with renovascular hypertension has created interest in the therapeutic potential of angiotensin II receptor antagonists, sympatholytic agents, and antioxidants. Therefore, we discuss the therapeutic utility of PTRA and stenting and the above-mentioned medications in patients with RAS and renal dysfunction.

Angioplasty, Balloon↗
PubMed2004

[Inadequate involvement of nephrologist/dialysis physicians in transplantation: based on the findings of a survey of transplant recipients].

The number of kidney transplantations(KTx) performed annually in Japan remains small even after enactment of the "Organ Transplant" law. One of the reasons for this paucity of KTx might be because most nephrologists or dialysis physicians who provide medical care to potential transplant candidates have little knowledge of KTx and are seldom involved in the care of recipients and donors. The extent to which Japanese physicians participate in KTx has not been well studied. We sent questionnaires to the 212 kidney transplant recipients who have received an allograft at Tokyo Women's Medical University and conducted a survey to examine the extent to which nephrologists or dialysis physicians are involved in KTx. There were 149 recipients, consisting of 95 males and 54 females with an average age of 46.5 years, who responded to the questionnaire. Only 23% of the patients had considered KTx before dialysis access placement. Lack of information on KTx was suspected for this delay in considering KTx. In fact, only 18% of patients were informed about KTx by their nephrologists before starting dialysis and as many as 49% did not receive any information at all. Forty-eight percent of the patients were not provided with the information even on registration for a cadaveric transplant list by their physicians. Only 20% of the patients received some information about KTx through their nephrologists. On the other hand, nearly 100% of patients think it is essential for nephrologists or dialysis physicians to provide information on KTx especially before the initiation on dialysis access. In addition, almost all of the patients would prefer nephrologists or a dialysis physician to participate in the care of transplant patients from the stage of preoperative evaluation through the post-transplant follow-up period. In conclusion, nephrologists or dialysis physicians have not provided information on KTx to their patients appropriately and most of the transplant recipients expect them to participate in KTx. Nephrologists and dialysis physicians need fundamental knowledge about KTx so that they can provide appropriate information to patients with end-stage renal disease.

Clinical Competence↗
PubMed2002

Adrenomedullin, an endogenous peptide, counteracts cardiovascular damage.

BACKGROUND: Adrenomedullin (AM), a potent vasodilator peptide, is produced by posttranslational splicing of pro-adrenomedullin together with proadrenomedullin N-terminal 20 peptide (PAMP), another hypotensive peptide. Although both AM and PAMP have the potential not only to decrease blood pressure but also to protect organs from damage, there is no direct evidence for their individual physiological roles in vivo. METHODS AND RESULTS: Using knockout mice with the disruption of AM peptide alone, we investigated the organ-protective effect of AM. Although the AM(-/-) mutation in mice was embryonic lethal without any apparent phenotypic changes, AM(+/-) mice were viable and fertile; plasma and organ AM concentrations were almost half of those in AM(+/+) mice. With the administration of angiotensin II (Ang II) on a high-salt diet for 12 days, marked perivascular fibrosis and intimal hyperplasia were found in coronary arteries of Ang II/salt-treated AM(+/-) mice, without the AM upregulation that was observed in Ang II/salt-treated AM(+/+) mice. In AM(+/-) mice, Ang II/salt loading increased both urinary excretion of 8-hydroxydeoxyguanosine and isoprostane, markers of oxidative stress. Consistently, immunostaining of both p67phox and gp91phox, subunits of NAD(P)H oxidase and 3-nitrotyrosine, the metabolites of reactive oxygen species (ROS), and the generation of ROS measured by electron spin resonance spectroscopy apparently increased in the Ang II/salt-treated heart. These data suggested that the overproduction of oxidative stress might be involved in the cardiovascular changes induced by Ang II/salt loading. CONCLUSIONS: The evidence presented supports the hypothesis that endogenous AM possesses a protective action against cardiovascular damage, possibly through the inhibition of oxidative stress production.

Adrenal Glands↗
PubMed2002

Feasibility of adequate solute clearance in obese patients on peritoneal dialysis: a cross-sectional study.

BACKGROUND: It is widely assumed that obese patients are poorly suited for peritoneal dialysis (PD). Mathematical models predicting weight limits to achieve adequate solute clearance in anuric patients on continuous ambulatory PD therapy do not apply to the majority of obese patients on PD therapy. METHODS: To define the extent to which obesity or large body size interferes with successful PD, the feasibility of achieving adequate solute clearance, defined by the Kidney Disease Outcomes Quality Initiative (K/DOQI) guidelines, was studied. We reviewed prospectively recorded data for 25 obese patients (body mass index > or = 29) from a group of 58 prevalent PD patients treated in an inner-city ambulatory dialysis center. Adequacy of solute clearances was assessed by comparing weekly Kt/V and weekly creatinine clearance (WCC) with those recommended by the K/DOQI. Adequacy also was examined separately for large patients, defined as those with total-body water (TBW) by the Watson and Watson equation of 48 L or greater. Similar analyses were performed separately for 10 anuric obese patients. RESULTS: Eighty four percent and 88% of the 25 obese patients achieved K/DOQI targets for weekly Kt/V and WCC, respectively. Among the 10 anuric obese patients, 90% and 70% achieved these targets. Only 60% of those with TBW of 48 L or greater met the Kt/V target. CONCLUSION: PD remains a viable option for obese patients with end-stage renal disease. It is possible for the majority of obese patients on PD therapy to achieve solute clearances recommended by the K/DOQI.

Body Mass Index↗