Detection and avoiding ventricular suction of ventricular assist devices

Continuous flow blood pumps, such as axial flow and centrifugal pumps, have been gaining interest as circulatory devices for total artificial hearts (TAHs) and a biventricular assist device (BVAD) because of their smaller size and simpler structure compared to pulsatile pumps. However, continuous flow pumps are more prone to suction of the left ventricle than pulsatile pumps are. Sudden increases in flow rate to meet changes in physiological demand, especially in the left pump, often cause ventricle suction. In this study, a control algorithm to prevent suction from occurring in the left ventricle by controlling the rotational speed of the right pump, instead of reducing the cardiac output of the left pump, was developed and investigated. The method was tested in acute animal experiments with calves. The results indicate that this proposed method is capable of preventing suction and could simultaneously maintain circulatory control. A key advantage of this control system is that flow rates can be maximized while avoiding ventricle suction conditions particularly when the circulatory system is unstable such as in a the first few days after operation.

Glucagon-like peptide-1 receptor agonist ameliorates renal injury through its anti-inflammatory action without lowering blood glucose level in a rat model of type 1 diabetes

AIMS/HYPOTHESIS

Glucagon-like peptide-1 (GLP-1) has various extra-pancreatic actions, in addition to its enhancement of insulin secretion from pancreatic beta cells. The GLP-1 receptor is produced in kidney tissue. However, the direct effect of GLP-1 on diabetic nephropathy remains unclear. Here we demonstrate that a GLP-1 receptor agonist, exendin-4, exerts renoprotective effects through its anti-inflammatory action via the GLP-1 receptor without lowering blood glucose.

METHODS

We administered exendin-4 at 10 μg/kg body weight daily for 8 weeks to a streptozotocin-induced rat model of type 1 diabetes and evaluated their urinary albumin excretion, metabolic data, histology and morphometry. We also examined the direct effects of exendin-4 on glomerular endothelial cells and macrophages in vitro.

RESULTS

Exendin-4 ameliorated albuminuria, glomerular hyperfiltration, glomerular hypertrophy and mesangial matrix expansion in the diabetic rats without changing blood pressure or body weight. Exendin-4 also prevented macrophage infiltration, and decreased protein levels of intercellular adhesion molecule-1 (ICAM-1) and type IV collagen, as well as decreasing oxidative stress and nuclear factor-κB activation in kidney tissue. In addition, we found that the GLP-1 receptor was produced on monocytes/macrophages and glomerular endothelial cells. We demonstrated that in vitro exendin-4 acted directly on the GLP-1 receptor, and attenuated release of pro-inflammatory cytokines from macrophages and ICAM-1 production on glomerular endothelial cells.

CONCLUSIONS/INTERPRETATION

These results indicate that GLP-1 receptor agonists may prevent disease progression in the early stage of diabetic nephropathy through direct effects on the GLP-1 receptor in kidney tissue.

Development of an Artificial Myocardium using a Covalent Shape-memory Alloy Fiber and its Cardiovascular Diagnostic Response

The authors have been developing a newly-designed totally-implantable artificial myocardium using a covalent shape-memory alloy fibre (Biometal®, Toki Corporation), which is attached onto the ventricular wall and is also capable of supporting the natural ventricular contraction. This mechanical system consists of a contraction assistive device, which is made of Ti-Ni alloy. And the phenomenon of the martensitic transformation of the alloy was employed to achieve the physiologic motion of the device. The diameter of the alloy wire could be selected from 45 to 250μm. In this study, the basic characteristics of the fiber of 150μm was examined to design the sophisticated mechano-electric myocardium. The stress generated by the fiber was 400gf under the pulsatile driving condition (0.4W, 1Hz). Therefore it was indicated that the effective assistance might be achieved by using the Biometal shape-memory alloy fiber.

Dynamic response of the pulmonary circulation in continuous flow artificial heart systems

Pulmonary circulation dynamics is important when considering bi-ventricular assist devices (BiVAD) or total artificial heart (TAH) systems and in investigating the mechanism of atrial collapse in order to design better control algorithms. In this study, we investigated pulmonary circulation dynamics in a continuous flow artificial heart system by performing acute tests on a mature goat. By varying the right pump speed, we were able to observe the dynamic response of the left atrial pressure (LAP) and simulate conditions that result in atrial suction. The results showed a time constant characteristic of a compliance lag in LAP response to changes in right pump output in the TAH configuration. These results may prove useful in the design of a new mock circulatory system that incorporates the dynamics of the pulmonary circulation, and in the improvement of existing control algorithms that prevent atrial wall collapse.

Erythromycin ameliorates renal injury via anti-inflammatory effects in experimental diabetic rats

AIMS/HYPOTHESIS

Recent studies have shown that the inflammatory process is involved in the pathogenesis of diabetic nephropathy. Fourteen-membered ring macrolides, including erythromycin, have anti-inflammatory, as well as antibacterial effects. The aim of this study was to investigate the renoprotective effects of erythromycin in streptozotocin (STZ)-induced diabetic rats.

METHODS

STZ-induced diabetic rats were treated orally with erythromycin (5 mg/kg body weight) or vehicle every day for 8 weeks. To evaluate the effect of erythromycin treatment, we measured urinary albumin excretion, and examined the following in the kidney: histological changes, the expression of intercellular adhesion molecule-1 (ICAM-1), macrophage infiltration, and nuclear factor-kappa B (NF-kappaB) activity.

RESULTS

Erythromycin significantly reduced urinary albumin excretion without affecting blood glucose levels and blood pressure. Erythromycin also attenuated glomerular hypertrophy, mesangial expansion, macrophage infiltration and ICAM-1 expression in renal tissues. The expression of the gene encoding TGFB1 (also known as TGF-beta1), type IV collagen protein production and NF-kappaB activity in renal tissues were increased in diabetic rats and reduced by erythromycin treatment.

CONCLUSIONS/INTERPRETATION

Erythromycin prevented renal injuries without changes of blood glucose levels and blood pressure in experimental diabetic rats. These results suggest that the renoprotective effects of erythromycin are based on its anti-inflammatory effect via suppression of NF-kappaB activation. Modulation of microinflammation with erythromycin may provide a new approach for diabetic nephropathy.

Cytotoxic mechanisms of inhibitor of RNA synthesis, 1-(3-C-ethynyl-beta-D-ribo-pentofuranosyl)cytosine (ECyd, TAS-106)

We investigated the molecular mechanisms of cell death induced by 1-(3-C-ethynyl-beta-D-ribo-pentofuranosyl)cytosine (ECyd, TAS-106: Figure 1), a potent inhibitor of RNA synthesis, using mouse mammary tumor FM3A cells and human fibrosarcoma HT1080 cells. ECyd induced the characteristics of apoptosis on these cells, such as morphological changes, DNA fragmentations and caspase-3-like protease activation. General caspases inhibitor (Z-Asp-CH2-DCB) inhibited cell death. Interestingly, we also found that ECyd induced rRNA fragmentation with the size of 3.2, 2.8 and 1.5 kb, and which might be caused by inhibition of RNA synthesis. rRNA fragmentation was mainly occurred in D8 domain of 28 S rRNA, and the end of 5'-terminal sequence of 1.5 kb fragment was C3220pC3221p or C3221pG3222p, that was identical to the recognition sequence of RNase L. Furthermore, the fragmentation patterns of rRNA digested with RNase L resembled that of ECyd treated cells in shape. These results indicate that antitumor mechanisms of ECyd are involved in activation of RNase L. rRNA fragmentation may be one of the death events as a result of inhibition of RNA synthesis and play an important role in the antitumor activity of ECyd.

Preventive effect of sulphated colominic acid on P-selectin-dependent infiltration of macrophages in experimentally induced crescentic glomerulonephritis

Leucocytes infiltrate into renal tissue and are involved in the pathogenesis of crescentic glomerulonephritis. The initial event in the process of leucocyte infiltration is characterized by selectin-mediated leucocyte rolling on endothelial surface. Role of selectins in pathogenesis of glomerulonephritis has still been controversial. Sulphated glycolipids and sulphated polysaccharides interfere with the binding of P- and L-selectin with carbohydrate ligands on endothelial cells or on leucocytes. Here we evaluated the role of selectins and the preventive effects of sulphated colominic acid (SCA), a synthetic sulphated polysaccharide, on experimental crescentic glomerulonephritis in Wistar-Kyoto (WKY) rats. Crescentic glomerulonephritis was induced by injection of nephrotoxic serum (NTS) in WKY rats. Rats subsequently received intraperitoneal injection of saline, neutralizing or non-neutralizing monoclonal antibody (mAb) to rat P-selectin and L-selectin, SCA (5 or 10mg/kg/day) or nonsulphated colominic acid (CA) (10mg/kg/day) for 2 weeks. Localization of P-, E-selectin, ligands for L-selectin and intraglomerular leucocytes was examined by immunohistochemistry. Gene expression of platelet-derived growth factor (PDGF) B chain in glomeruli was quantified using real-time RT-PCR. P-selectin was highly expressed on glomerular endothelial cells after injection of NTS, whereas E-selectin and L-selectin ligands were not detected. Anti-P-selectin mAb, but not anti-L-selectin mAb, significantly reduced glomerular infiltration of macrophages, crescent formation, and proteinuria. SCA also reduced proteinuria, macrophage infiltration, and crescent formation in a dose-dependent manner. Furthermore, SCA suppressed gene expression of PDGF B chain in glomeruli. Our results indicate that P-selectin partially mediates glomerular infiltration of macrophage in experimental crescentic glomerulonephritis. Moreover, SCA may inhibit intraglomerular infiltration of macrophages by interfering with P-selectin-dependent adhesion pathway, and progression of experimental crescentic glomerulonephritis.

Posture-related changes in the pressure environment of the ventriculoperitoneal shunt system

OBJECT

The purpose of this study is to clarify the whole pressure environment of the ventriculoperitoneal (VP) shunt system in patients with successfully treated hydrocephalus and to determine which factor of the pressure environment has a preventive effect on overdrainage.

METHODS

Thirteen patients with hydrocephalus who had been treated with VP shunt therapy by using a Codman-Hakim programmable valve without incidence of overdrainage were examined. The authors evaluated intracranial pressure (ICP), intraabdominal pressure (IAP), hydrostatic pressure (HP), and the perfusion pressure (PP) of the shunt system with the patients both supine and sitting. With patients supine, ICP, IAP, and HP were 4.6 +/- 3 mm Hg, 5.7 +/- 3.3 mm Hg, and 3.3 +/- 1 mm Hg, respectively. As a result, the PP was only 2.2 +/- 4.9 mm Hg. When the patients sat up, the IAP increased to 14.7 +/- 4.8 mm Hg, and ICP decreased to-- 14.2 +/- 4.5 mm Hg. The increased IAP and decreased ICP offset 67% of the HP (42.9 +/- 3.5 mm Hg), and consequently the PP (14 +/- 6.3 mm Hg) corresponded to only 33% of HP.

CONCLUSIONS

The results observed in patients indicated that IAP as well as ICP play an important role in VP shunt therapy and that the increased IAP and the decreased ICP in patients placed in the upright position allow them to adapt to the siphoning effect and for overdrainage thereby to be avoided.

Isolated dilation of the trigono-inferior horn--four case reports

Four patients presented with isolated dilation of the trigono-inferior horn associated with either mass lesion at the trigone of the lateral ventricle or with shunt over-drainage. We investigated clinical symptoms, course, and neuroradiological findings of these cases. The pressure of the isolated ventricle was measured or estimated at surgery in all cases. The common symptoms were recent memory disturbance and contralateral homonymous hemianopia. Contralateral hemiparesis was observed occasionally. Rapid deterioration of the isolation caused uncal herniation in one case. Comma-shaped dilation of the inferior horn was observed in all cases. Midline shift was not conspicuous except in one case. Intraventricular pressure at surgery was 18 cmH2O, 35 cmH2O, 3 cmH2O, and within normal range. These cases had very similar clinical symptoms and neuroradiological findings. The pathophysiology of isolation suggested three types of isolation (high-, normal-, and low-pressure isolation), depending on the pressure of the isolated ventricle. The isolation of trigono-inferior horn is an important clinical entity as it may cause uncal herniation in patients with high-pressure lesions.

Pseudomalabsorption of levothyroxine: a case report

A 51-year-old woman who had been treated with levothyroxine sodium because of hypothyroidism after total thyroidectomy for thyroidal cancer was admitted to our hospital for persistent hypothyroidism despite large dose administration of levothyroxine (600 microg/day). The patient complained of severe general fatigue and body weight gain. Free thyroxine, free triiodothyronine and thyrotropin levels were 0.97 ng/dl, 1.55 pg/ml and 24.51 microU/ml, respectively, under oral administration of levothyroxine. Levothyroxine loading test performed by liquid form, pulverized tablets via nasogastric tube and intravenous administration revealed no evidence of malabsorption or metabolic disorder of levothyroxine, although oral intake of tablets was ineffective due to her factitiousness. We report here a possible case of "pseudomalabsorption of levothyroxine" to emphasize the clinical recognition of this disorder in patients with resistant hypothyroidism.

Lung cancer associated with pulmonary bulla. case report and review of literature

A few reports have suggested the possible association between lung cancer and bullous disease. We report a surgical case of lung adenocarcinoma located in close proximity to pulmonary bullae. A 48-year-old nonsmoker, asymptomatic male was found to have a pulmonary tumor mass and giant bulla in the right lung. Thoracotomy identified a tumor arising from a firm, scarred and contracted area close to the bulla wall. Based on this report and review of other cases in the literature, we emphasize the need for physicians to be aware of the potential development of lung cancer in patients with pulmonary bulla.

Spontaneous regression of malignant lymphoma of the stomach

We report a case of complete and spontaneous regression of malignant lymphoma of the stomach. A submucosal tumor with central ulceration was detected on the greater curvature of the stomach in a 63-year-old woman. The tumor was diagnosed histopathologically as a diffuse large B-cell lymphoma (REAL classification). The tumor disappeared 18 days later without chemotherapy. Examination at that stage showed Helicobacter pylori (H. pylori), which was later treated with antibiotics. There was no evidence of recurrence of the malignant lymphoma at the last follow-up conducted at the time of preparation of this report, 13 months after the initial diagnosis. Spontaneous regression of an intermediate and high-grade non-Hodgkin's lymphoma is uncommon. We discuss the possible role of H. pylori in the regression of gastric malignant lymphomas.

Integrins mediate the inhibitory effect of focal adhesion on angiotensin II-induced p44/42 mitogen-activated protein (MAP) kinase activity in human mesangial cells

Previously, we reported that the formation of focal adhesion accelerated by accumulation of extracellular matrices may inhibit the angiotensin II-stimulated proliferation of human mesangial cells (HMCs). The process is regulated by p44/42 MAP kinase activity through the mediation of paxillin and GTPase activating proteins. In this report, we investigated the effect of integrin molecules on the angiotensin II-induced p44/42 MAP kinase activation in non-adherent HMCs. The results demonstrated that incubation of cells with both antibody to integrin beta(1) chain (K20) and GRGDS peptide induced integrin clustering, paxillin aggregation, and marked suppression of angiotensin II-induced p44/42 MAP kinase activation. On the other hand, incubation of cells with K20 alone induced integrin clustering without paxillin aggregation and the suppressive effect on angiotensin II-stimulated p44/42 MAP kinase activity. Our results strongly suggest the pivotal role of integrins in the inhibitory effect of focal adhesion on p44/42 MAP kinase activity, the checking system against angiotensin II-induced MAP kinase overactivation.

A clinical survey of hydrocephalus and current treatment for hydrocephalus in Japan: analysis by nationwide questionnaire

We analyzed current treatment for hydrocephalus in Japan by means of a nationwide questionnaire. Ventriculoperitoneal (VP) shunting was the most common form of cerebrospinal fluid (CSF) shunting, and in 66% of cases the ventricular catheter was inserted via the anterior horn. Various types of flow-control valves were used in 46% of CSF shunting procedures, and the proportion of cases in which such valves are used seems to be increasing. The Codman-Hakim valve was used most frequently, followed by the Sophy valve. The initial pressure setting of programmable pressure valves was selected in 82% of institutes on the basis of the CSF pressure obtained during the shunt operation. Most flow-control valves were implanted in the retroauricular region; however, Sophy valves were implanted in the chest wall in a high percentage of cases. The rate of shunt complications was significantly lower among VP shunt cases with flow-control valves than in those without flow-control valves. The most common cause of shunt complications was trouble with the abdominal catheter. These results will contribute to progress in the treatment for hydrocephalus.

[Hemodynamics of the transverse sinus using cine angiography]

Numerous anatomical observations of the transverse sinus (TS) have been reported and features of this sinus, as assessed by cerebral angiography, are referred to in many monographs. However, there are no studies on the hemodynamics in the TS. We recently investigated the TS, using cerebral angiography with cinematographic films. The subjects were 35 patients who underwent angiography of 3 or 4 vessels at our institute, using Seldinger's method. The contrast material was infused manually. Cinematography permitted observation of the size of the bilateral TS and the direction of blood flow. Depending on the features of the bilateral TS, the patients could be divided into three groups. Type I (cases where the right TS was dominant) accounted for the highest percentage (54.3%, 19/35). In 11 of these 19 cases, the left TS also showed antegrade blood flow. In 6 of the Type I group, the blood flow through the left TS was in two directions (towards the Torcular Herophili and towards the left sigmoid sinus). In the other two cases rated as Type I, the blood flow through the left TS was in the direction from the Torcular Herophili to the right TS. Fourteen cases (40.0%) were rated as Type II (in which both sinuses were similar in size). In 13 of these 14 cases, blood flow through the bilateral TS was almost symmetrical (Type II-A). In one of the 14 cases, the blood flow through the left TS was in two directions (towards the Torcular Herophili and towards the left sigmoid sinus).

Chopstick penetration of the posterior cranial fossa: case report

A very rare case of wooden foreign body intrusion into the posterior cranial fossa is reported. The patient, a 16-month-old girl, fell down while holding chopsticks and was injured in the right pre-auricular region. Computed tomographic scans revealed a linear low-density area ranging from the right external auditory meatus to the fourth ventricle through the petrous portion of the temporal bone, passing near the middle cerebellar peduncle. Right temporal craniotomy was performed to abrade the petrous bone, resulting in removal of the chopstick fragment. The patient had an uneventful postoperative course and was discharged in ambulant condition, only with right hearing difficulty.

Traumatic intracranial foreign body embolization--case report

A 27-year-old male presented with intracranial embolization due to accidental penetration of his neck by an iron fragment at work. Cerebral angiography revealed foreign body embolization of the left middle cerebral artery. The foreign body was successfully removed via craniotomy and arteriotomy. The extended period from onset to surgical treatment prevented acute hemodynamic reconstruction. However, he had good collateral circulation and was discharged with mild hemiparesis and moderate motor aphasia. The possibility of intracranial embolization should be considered in patients presenting with penetrating injury of the neck.