Pathogenesis of diabetic retinopathy and the renin-angiotensin system.

Despite the beneficial effects of good glycaemic control, loss of vision because of diabetic retinopathy (DR) still occurs. Recent studies have suggested that hypertension is a risk factor for the development and progression of DR and that blood pressure reduction can delay the progression of retinopathy. The renin-angiotensin system is activated by chronic hyperglycaemia, and the vitreous fluid level of angiotensin II (AII) is elevated in patients with proliferative diabetic retinopathy and diabetic macular oedema. AII increases vascular permeability and promotes neovascularization. It has been suggested that an autocrine-paracrine relationship may exist between AII and vascular endothelial growth factor in the ocular tissues. Accordingly, angiotensin-converting enzyme inhibitors or AII Type 1 (AT1) receptor blockers may be useful therapeutic agents for preventing the progression of DR.     

Sialylated Lewis x as a tumor-associated antigen in stomach cancer

Sialylated Lewis (S-Lex) has been studied histologically and serologically in stomach cancer by the CSLEX1 monoclonal antibody. S-Lex was expressed in 73.9% of 46 stomach cancer tissues, 29.4% of metaplastic parts adjacent to cancer, and none of six gastric ulcer tissues including metaplasia. Serologically positive percentages were as follows: 26.0% of 100 stomach cancers, 0.9% of 322 benign diseases, and 0.7% of 280 healthy donors in the sera, as well as 72.4% of 29 ascites of stomach cancers and 5.3% of 17 effusions of benign diseases. These findings demonstrate that S-Lex possesses a potential usefulness as a tumor marker in stomach cancer.     

Can pretreatment ADC values predict recurrence of bladder cancer after transurethral resection?

Objective

The aim of this retrospective study was to investigate the association between the pretreatment apparent diffusion coefficient (ADC) value and recurrence of bladder cancer after transurethral resection.

Methods

Patients with superficial bladder cancer were identified. Mean ADC values of the tumors were compared between patients with and without recurrence following trans-urethral resection. A receiver–operator characteristic curve was used for determining the optimal cutoff ADC value. Univariate and multivariate analyses were used to determine the effect of ADC values and other factors.

Results

With a mean follow-up period of 25 months, bladder cancer recurred in 14 of 44 patients (32%). The mean ADC value of tumors in patients with recurrence was lower than in those without recurrence (1.08 mm²/s vs. 1.28 × 10⁻³ mm²/s; p = 0.003). The optimal cutoff ADC value for predicting recurrence was determined to be 1.12 × 10⁻³ mm²/s. A modest and significant negative correlation was observed between the ADC values and tumor size (r = −0.436, p = 0.008). After adjustment for size and risk groups, an ADC value equal to or less than the optimal cutoff remained a significant predictor of recurrence (odds ratio 6.3, 95% CI 1.23–32.2, p = 0.027).

Conclusion

Pretreatment ADC values may be an independent predictor of bladder cancer recurrence.     

Pigment epithelium-derived factor is related to macular microcirculation in patients with macular edema and branch retinal vein occlusion

To investigate the correlation between the perifoveal capillary blood flow velocity (BFV) and the vitreous level of pigment epithelium-derived factor (PEDF) in patients with branch retinal vein occlusion (BRVO) and macular edema. In a retrospective interventional study of patients with BRVO and macular edema, undiluted vitreous specimens were obtained from 12 eyes of 12 patients. The level of PEDF was then measured in vitreous samples by an enzyme-linked immunosorbent assay. Before vitreous fluid sampling, perifoveal capillary BFV was measured by fluorescein angiography with a scanning laser ophthalmoscope and the tracing method. Subsequently, the relationship between perifoveal capillary BFV and the vitreous level of PEDF was investigated. There was a significant positive correlation between BFV and the vitreous level of PEDF in the 12 patients (ρ?=?0.75, p?=?0.013). The vitreous level of PEDF may influence macular microcirculation in patients with BRVO and macular edema.     

Macular microcirculation in patients with epiretinal membrane before and after surgery

Background

To investigate blood flow velocity (BFV) in the perifoveal capillaries before and after vitreous surgery for patients with epiretinal membrane (ERM).

Methods

Twenty-one eyes in patients with ERM and 16 eyes in healthy subjects were involved in this study. Fluorescein angiography was performed using a scanning laser ophthalmoscope and BFV was analyzed by the tracing method. Foveal thickness (FT) was measured by optical coherence tomography.

Results

BFV was significantly slower in the ERM patients (1.04?±?0.10?mm/s) than in the healthy subjects (1.49?±?0.11?mm/s ) (p?=?0.0010). BFV in the ERM patients 6?months after vitreous surgery (6?M) (1.21?±?0.02?mm/s) significantly increased compared with BFV before surgery (0?M) (1.04?±?0.10?mm/s) (p?=?0.0061). BFV 1?year after vitreous surgery (1?Y) significantly increased (1.38?±?0.02?mm/s) compared with BFV(6?M) (1.21?±?0.02?mm/s) (p?=?0.0235). FT was significantly greater in the ERM patients (351.7?±?87.1?μm) than in the healthy subjects (158.9?±?16.9?μm) (p?=?0.0011). FT (6?M) significantly decreased (285.3?±?36.9?μm) compared with FT before surgery (0?M) (351.7?±?87.1?μm) (p?=?0.0212). FT did not show significant differences between (6?M) and (1?Y). No significant correlation was found between BFV and FT before surgery.

Conclusions

Perifoveal capillary BFV in patients with ERM was slower than that in the healthy subjects, and significantly improved after vitreous surgery as time progressed. It can be said that perifoveal capillary BFV is related to the development and improvement of ERM in the long term.     

Cerebral blood flow response to PaCO2 during hypothermic cardiopulmonary bypass in rabbits

Differences in cerebral blood flow (CBF) between alpha-stat and pH-stat management depend on preserved responsiveness of the cerebral vasculature to changes in arterial carbon dioxide tension (PaCO2). We tested the hypothesis that hypothermia-induced reductions in CBF would decrease the CBF response to changing PaCO2 (delta CBF/delta PaCO2). Anesthetized New Zealand white rabbits were randomly assigned to one of three temperature groups--group 1 (37 degrees C, n = 9); group 2 (31 degrees C, n = 10); or group 3 (25 degrees C, n = 10)--and were cooled using cardiopulmonary bypass. After esophageal temperature equilibration (approximately 40 min), oxygenator gas flows were serially varied to achieve PaCO2 values of 20, 40, and 60 mm Hg (temperature-corrected). All animals were studied at all three PaCO2 levels in random order. At each level of PaCO2, CBF and masseter blood flow were determined using radiolabeled microspheres. There were no significant differences between groups with respect to mean arterial pressure (approximately 80 mmHg), central venous pressure (approximately 4 mmHg), or hematocrit (approximately 22%). Prior normothermic studies have found delta CBF/delta PaCO2 to be proportional to CBF. Nevertheless, in this study, with hypothermia-induced reductions in CBF, delta CBF/delta PaCO2 was not significantly different between temperature groups. Thus, hypothermia either increased the sensitivity of the cerebral vasculature to carbon dioxide and/or increased the effective level of cerebrospinal fluid respiratory acidosis produced by each increment of temperature-corrected PaCO2.(ABSTRACT TRUNCATED AT 250 WORDS)     

Suppression of catechol-O-methyltransferase activity through blunting of alpha2-adrenoceptor can explain hypertension in Dahl salt-sensitive rats.

Catecholamines have been reported to be involved in the development of salt-sensitive hypertension. We investigated the relation between catechol-O-methyltransferase (COMT) and salt-sensitivity. In the first experiment, Dahl salt-sensitive (DS) rats were given a normal-salt (NS), high-salt (HS), or HS+hydralazine (80 mg/l water) diet for 4 or 13 weeks, and Dahl salt-resistant (DR) rats were given a NS or HS diet. COMT activities in both the kidneys and liver and urinary norepinephrine (NE) and dopamine (DA) excretion were measured. In the second experiment, HepG2 cells were used to investigate the role of NE in regulating COMT activity. In the third experiment, we investigated the reactivity of pre- and postsynaptic alpha(2)-adrenoceptor (AR) in DS rats. HS loading significantly suppressed the activities of membrane-bound COMT (MB-COMT) and, consistent with this finding, increased the urinary NE level in DS rats, but not in DR rats. Hydralazine did not restore the MB-COMT activities, which suggested that HS loading rather than elevated blood pressure suppressed the MB-COMT activities. The in vitro experiment using HepG2 cells revealed that NE increased the MB-COMT activity via the alpha(2)-AR. However, both the pre- and postsynaptic alpha(2)-AR reactivity was decreased by HS loading in DS rats. In conclusion, HS intake suppresses the MB-COMT activities in DS rats, presumably by blunting alpha(2)-AR signaling. The suppression of MB-COMT activities, consequent decrease in degradation of NE, and increase in NE release by blunting of alpha(2)-AR function may be involved in the development of salt-sensitive hypertension in DS rats, in whom DA-dependent natriuresis may be suppressed.     

Comparison of monoclonal and polyclonal enzyme-linked immunoabsorbent (elisa) assays for serum lp(a) and differences in reactivities to lp(a) phenotypes

We have prepared a monoclonal antibody to Lipoprotein(a)[Lp(a)] and have used it to develop an ELISA test for assaying Lp(a) in serum. The monoclonal antibody employed in the assay system reacts uniformly with S1,S2,S3 and B phenotypes of isoforms, and no cross-reaction with plasminogen at a concentration of 100 mg/dL was observed. Results of the monoclonal ELISA assay were similar to those obtained with a polyclonal antibody ELISA method and demonstrated a correlation coefficient, r=0.99 with the equation for the regression line: Y(proposed)= 1.06 X (polyclonal antibody reference ELISA test) = 0.36(N = 51). Inter- and intra-assay precision(CVs) of the monoclonal ELISA assay were between 2.2–3.6% at a mean Lp(a) concentration range of 19.1–68.2 mg/dL,(N = 12). Assay results of various standards were compared by both monoclonal and polyclonal antibody ELISA tests. We observed some discrepancies between expected concentrations and the polyclonal antibody ELISA assay results, which is thought to be more uniformly reactive to the various Lp(a) phenotypes. The monoclonal antibody employed in our proposed method reacts uniformly with Lp(a) phenotypes, and the assay exhibits excellent sensitivity, specificity, and accuracy and is well suited for clinical use.©1995 wiley-Liss, inc.     

Production and characterization of monoclonal antibodies to Fc gamma 2a-binding protein isolated from the detergent lysate of a murine macrophagelike cell line, P388D1

Hybridoma cell lines were produced by fusion of SP2/0 murine myeloma cell line with the spleen cells of Wister rats which were immunized with IgG2a-binding protein isolated from the detergent lysate of a murine macrophagelike cell line, P388D1, by affinity chromatography on IgG-Sepharose 4B. A monoclonal clone (designated as 3A2) out of a total of 13 different antibody-secreting cell lines was found to secrete IgG1 class antibodies, which inhibited more than 70% of the binding of radio-iodinated myeloma IgG2a protein to P388D1 cells. The 3A2 Fab fragments bound specifically to P388D1 cells at 4 degrees C with a KD of 1.9 x 10(-8) M and Bmax of 2.9 x 10(5) per cell. This Fab fragment also specifically bound to Fc gamma 2a receptor (R)-positive T cell line (S49) with a KD of 4.4 x 10(-9) M and a Bmax of 1.0 x 10(4) but did not bind to Fc gamma 2a-negative S49 variant cell line, cyc-. The flow cytometric analysis with the use of fluorescein-isothiocyanate-tagged 3A2 F(ab')2 also showed that this antibody binds to Fc gamma 2aR-positive cells, P388D1 and S49, but not to Fc gamma 2aR-negative cells, cyc-. Monomeric and heat-aggregated IgG2a (13-fold molar excess) inhibited the binding of the radioiodinated 3A2 F(ab')2 to P388D1 cells by 70 and 49%, respectively, whereas the inhibition by monomeric and heat-aggregated IgG2b was 17 and 39%, respectively; 3A2 F(ab')2 (100-fold molar excess) inhibited the binding of IgG2a and IgG2b to P388D1 cells by 90 and 24%, respectively, whereas the inhibition of binding of these IgG to S49 cells was 79 and 49%, respectively. Western blotting analysis showed that 3A2 antibody recognizes a major protein (Mr = 100,000) and a minor component (Mr = 80,000) separated by SDS-PAGE of P388D1 or S49 cell lysates under nonreducing condition, whereas under reducing condition, this antibody recognized a major protein (Mr = 50,000) and two additional minor components (Mr = 40,000 and 35,000). Fc gamma 2aR may thus exist at the cell surface as a disulfide linked dimer of a subunit of Mr of 50,000, which could be partially degraded during the isolation to smaller fragments of 40,000 and 35,000 Mr peptides which are still held together by interchain disulfide bond.(ABSTRACT TRUNCATED AT 250 WORDS)