Retinal and choroidal vasculature in rats with spontaneous diabetes type 2 treated with the angiotensin-converting enzyme inhibitor cilazapril: corrosion cast and electron-microscopic study

The long-term effects of the angiotensin-converting enzyme (ACE) inhibitor cilazapril on retinal and choroidal circulation in rats with spontaneous diabetes type 2 were assessed by corrosion casts, scanning electron microscopy (SEM) and transmission electron microscopy. One group of 20 male Otsuka Long-Evans Tokushima Fatty (OLETF) rats was treated with 10 mg/kg/day of cilazapril from 4 to 64 weeks of age, and 20 other OLETF rats received no treatment. A third group, 20 male Long-Evans Tokushima Otsuka (LETO) rats, served as age-matched controls. At regular intervals, the rats were weighed, and their blood glucose was measured. Before the experiment, their systolic blood pressure and total cholesterol level were determined. At 64 weeks of age, the OLETF rats weighed significantly less than the cilazapril-treated OLETF and the LETO rats (p < 0.0001). At the same age, 100% of the untreated OLETF rats had bilateral cataracts, while the lens was clear and no fundus abnormality was detected in the cilazapril-treated OLETF rats and the LETO rats. Cilazapril lowered systolic blood pressure to a nearly normal level, significantly prevented the increase in blood sugar and inhibited the increase in serum cholesterol in the OLETF rats throughout the treatment. In the 64-week-old OLETF rats without treatment, corrosion cast and SEM revealed diabetic retinal and choroidal vascular changes: tortuosity of the vessels, variations in caliber, narrowing of arteries, arterio-arteriolar anastomoses and hairpin loop formation in precapillary arterioles, sparse collecting venules in the choroid and marked capillary changes such as caliber irregularity, narrowing, tortuosity, loop formation and decreased capillaries, outpouching and microaneurysms. In the cilazapril-treated OLETF rats, these changes were markedly decreased to the level seen in the LETO rats, in which the retinal and choroidal blood vessels had a definite and fairly constant pattern and the capillaries were more regularly and densely arranged and had a remarkably uniform caliber. Our results show that the long-term administration of cilazapril before or from the initial onset significantly prevented the increase in blood sugar and inhibited the increases in serum cholesterol in OLETF rats throughout the treatment, lowered systolic arterial pressure to a nearly normal level and prevented diabetic ocular complications. The effects of cilazapril on the diabetic retinal and choroidal vasculature are described for the first time. SEM of corrosion casts is a valuable and easy technique for showing precisely and three-dimensionally the effects of some drugs on the vasculature.     

Two new triterpenoids from the fresh leaves of Psidium guajava

Two new triterpenoids, guajavolide (2 alpha,3 beta,6 beta,23-tetrahydroxyurs-12-en-28,20 beta-olide; 1) and guavenoic acid (2 alpha,3 beta,6 beta,23-tetrahydroxyurs-12,20(30)-dien-28-oic acid; 2) along with one known triterpene oleanolic acid (3) were isolated from the fresh leaves of Psidium guajava. Their structure elucidation and stereochemistry were determined by spectroscopic experiments, including 2D-NMR techniques.     

Evidence and mechanisms of retrogenesis in Alzheimer's and other dementias: management and treatment import

Retrogenesis is the process by which degenerative mechanisms reverse the order of acquisition in normal development. Alzheimer's disease (AD) and related conditions in the senium have long been noted to resemble "a return to childhood" Previously, we noted that the functional stages of AD precisely and remarkably recapitulated the acquisition of the same functional landmarks in normal human development. Subsequent work indicated that this developmental recapitulation also applied to the cognitive and related symptoms in AD. Remarkably, further investigations revealed that the same neurologic "infantile" reflexes, which mark the emergence from infancy in normal development, are equally robust indicators of corresponding stages in AD. Neuropathologic and biomolecular mechanisms for these retrogenic processes are now evident. For example, the pattern of myelin loss in AD appears to mirror the pattern of myelin acquisition in normal development. Also, recent findings indicate that mitogenic factors become reactivated in AD, and, consequently, the most actively "growing" brain regions are the most vulnerable. Because of this robust retrogenic process, the stages of AD can be translated into corresponding developmental ages (DAs). These DAs can account for the overall management and care needs of AD patients. A science of AD management can be formulated on the basis of the DA of the Alzheimer's patient, taking into consideration differences of AD from normal development as well as homologies.     

Costs and cost-effectiveness of different DOT strategies for the treatment of tuberculosis in Pakistan. Directly Observed Treatment

An economic study was conducted alongside a clinical trial at three sites in Pakistan to establish the costs and effectiveness of different strategies for implementing directly observed treatment (DOT) for tuberculosis. Patients were randomly allocated to one of three arms: DOTS with direct observation by health workers (at health centres or by community health workers); DOTS with direct observation by family members; and DOTS without direct observation. The clinical trial found no statistically significant difference in cure rate for the different arms. The economic study collected data on the full range of health service costs and patient costs of the different treatment arms. Data were also disaggregated by gender, rural and urban patients, by treatment site and by economic categories, to investigate the costs of the different strategies, their cost-effectiveness and the impact that they might have on patient compliance with treatment. The study found that direct observation by health centre-based health workers was the least cost-effective of the strategies tested (US dollars 310 per case cured). This is an interesting result, as this is the model recommended by the World Health Organization and International Union against Tuberculosis and Lung Disease. Attending health centres daily during the first 2 months generated high patient costs (direct and in terms of time lost), yet cure rates for this group fell below those of the non-observed group (58%, compared with 62%). One factor suggested by this study is that the high costs of attending may be deterring patients, and in particular, economically active patients who have most to lose from the time taken by direct observation. Without stronger evidence of benefits, it is hard to justify the costs to health services and patients that this type of direct observation imposes. The self-administered group came out as most cost-effective (164 dollars per case cured). The community health worker sub-group achieved the highest cure rates (67%), with a cost per case only slightly higher than the self-administered group (172 dollars per case cured). This approach should be investigated further, along with other approaches to improving patient compliance.     

Pharmacokinetics, toxicity, and efficacy of ends-modified raf antisense oligodeoxyribonucleotide encapsulated in a novel cationic liposome.

Raf-1 protein serine threonine kinase plays an important role in cell survival and proliferation. Antisense inhibition of Raf-1 expression has been shown to enhance the cytotoxic effects of radiation and anticancer drugs. Here we have evaluated the toxicity, pharmacokinetics, and antitumor efficacy of a novel formulation of liposome-entrapped raf antisense oligodeoxyribonucleotide (LErafAON). The LErafAON preparation showed high liposome entrapment efficiency of rafAON (>85%) and stability at room temperature. In CD2F1 mice, administration of LErafAON produced no morbidity/mortality (5-35 mg/kg/dose, i.v., x12). Dose-related elevations in liver enzymes (alanine aminotransferase and aspartate aminotransferase) and histopathological changes in liver were noted in LErafAON and blank liposome groups. No morbidity/mortality and changes in clinical chemistry or histopathology were observed in New Zealand white rabbits (3.75 mg/kg/dose, i.v., x8; 6.5 mg/kg/dose, i.v., x6) or in cynomolgous monkeys (3.75 or 6.25 mg/kg/dose, i.v., x9). Transient decrease in total hemolytic complement activity (approximately 62-74%) and increases in C3a (approximately 3-fold) and Bb levels (approximately 5-12-fold) were observed in LErafAON and blank liposome groups of monkeys. A 30 mg/kg i.v. dose of LErafAON in human prostate tumor (PC-3)-bearing BALB/c athymic mice gave a terminal plasma half-life of 27 h, and intact rafAON could be detected in plasma and in normal and tumor tissues for up to at least 48 h. In monkeys, the terminal plasma half-life of 30.36 +/- 23.87 h was observed at an i.v. dose of 6.25 mg/kg. LErafAON (25 mg/kg/dose, i.v., x10) or ionizing radiation (3.8 Gy/day, x5) treatment of PC-3 tumor-bearing athymic mice led to tumor growth arrest, whereas a combination of LErafAON and ionizing radiation treatments resulted in tumor regression. LErafAON treatment caused inhibition of Raf-1 protein expression in normal and tumor tissues in these mice (>50%, versus controls). These data have formed a basis of the clinical Phase I studies of LErafAON for cancer treatment.     

Epibatidine binding sites and activity in the spinal cord

Epibatidine has been shown to be the most potent nicotinic agonist in several neuronal nicotinic receptor preparations. Similar to other nicotinic agonists, intrathecal (−)-epibatidine elicits dose-dependent increases in pressor, heart rate and pain responses in rats, as well as an increase in latency to withdraw from a noxious thermal stimulus. The latter response requires higher doses and is of shorter duration, suggesting interaction with multiple subtypes of spinal nicotinic receptors. In the present study, we relate the binding properties of (±)-[³H]epibatidine in spinal cord membrane preparations to the cardiovascular and behavioral responses. Unlike (−)-[³H]cytisine or (−)-[³H]nicotine, (±)-[³H]epibatidine reveals two sites; the ratio of high affinity to low affinity sites is 2:1. The rank ordering of potencies of the nicotinic agonists in displacing (±)-[³H]epibatidine binding from spinal cord membranes correlates with the potencies in eliciting cardiovascular and behavioral responses upon spinal administration. The nicotinic receptor antagonists, α-lobeline, dihydro-β-erythroidine and methyllycaconitine, also displayed similar rank ordering of potencies in displacing (±)-[³H]epibatidine, (−)-[³H]cytisine or (−)-[³H]nicotine binding to spinal nicotinic receptors. Virtually all the nicotinic analogs exhibited a Hill coefficient of less than one in competing with (±)-[³H]epibatidine to spinal cord membranes indicating their interaction with at least two classes of binding sites. Intrathecal (−)-epibatidine, in addition to eliciting an initial and subsequently a sustained pressor and tachycardic response, also exhibited a transient intervening bradycardia which coincided temporally with the duration of the analgesia. Repeated administration of (−)-epibatidine desensitized its responses as well as the cardiovascular and behavioral responses to spinal nicotine and cytisine. Intrathecal α-lobeline showed selectivity for blocking the analgesic response, whereas methyllycaconitine exhibited selectivity for the pressor and irritation responses. The NMDA receptor antagonist, AP-5, inhibited the pressor, tachycardic and irritation responses elicited by intrathecal (−)-epibatidine, confirming a role for spinal excitatory amino acids released by the nicotinic agonist. © 1997 Elsevier Science B.V. All rights reserved.     

Combined autologous cellular cardiomyoplasty with skeletal myoblasts and bone marrow cells in canine hearts for ischemic cardiomyopathy

OBJECTIVES: Cellular cardiomyoplasty with isolated skeletal myoblasts and bone marrow mononuclear cells is an encouraging therapeutic strategy for heart failure. We investigated the achievements accomplished with combined cell therapy of skeletal myoblast and bone marrow mononuclear cell transplantation to the ischemic canine myocardium. METHODS: Autologous skeletal myoblasts (1 x 10(8)) and autologous bone marrow mononuclear cells (3 x 10(6)) were injected directly into the damaged myocardium of canine hearts that had undergone 2 weeks of left anterior descending coronary artery ligation. Treatment groups were as follows: skeletal myoblasts plus bone marrow mononuclear cells (combined cell therapy, n = 4), myoblasts (n = 4), bone marrow mononuclear cells (n = 4), and medium only (n = 4). In similarly designed supporting experiments, angiogenic factor expression was evaluated by enzyme-linked immunosorbent assay after cell transplantation in rat hearts that had undergone left anterior descending coronary artery ligation. RESULTS: Four weeks after cell implantation, echocardiography demonstrated better cardiac performance with reduced left ventricular dilation and significantly improved ejection fraction in the combined cell therapy group compared with that seen in the other groups (pretreatment, 37.7% +/- 1.1%, vs combined cell therapy, 55.4% +/- 8.6%; myoblasts, 47.4% +/- 7.4%; bone marrow mononuclear cells, 44.4% +/- 6.7%; medium only [control], 34.4% +/- 5.4%; P < .05). A significantly high number of neovessels were observed in the group receiving combined cell therapy only (combined cell therapy, 45.5 +/- 12 x 10(2)/mm2; myoblasts, 26.5 +/- 8 x 10(2)/mm2; bone marrow mononuclear cells, 30.7 +/- 15 x 10(2)/mm2; medium only [control], 7.1 +/- 1 x 10(2)/mm2; P < .05). Immunostained sections expressed the skeletal specific marker myosin heavy chain, although they did not express the cardiac specific marker troponin T. Results of enzyme-linked immunosorbent assay showed the highest expression of vascular endothelial growth factor (combined cell therapy, 2.9 +/- 0.7 ng/g tissue; myoblasts, 0.24 +/- 0.7 ng/g tissue; bone marrow mononuclear cells, 1.9 +/- 0.2 ng/g tissue; medium only [control], 0.19 +/- 0.004 ng/g tissue; P < .05) and hepatocyte growth factor in the combined cell therapy hearts. CONCLUSIONS: Combined autologous cellular therapy induced both myogenesis and angiogenesis with enhancement of cardiac performance and reduction of cardiac remodeling, suggesting a capable strategy for treating severe ischemic cardiomyopathy clinically.     

A comparison of 250 and 500 mL of terminal warm blood cardioplegia after global myocardial ischemia: a prospective randomized study

BACKGROUND: Controlled reperfusion with terminal warm blood cardioplegia (TWBC) improves myocardial performance after global ischemia. However, the optimum volume required is unknown. METHODS: Fifty patients undergoing elective coronary artery bypass graft surgery were prospectively randomized to receive either 250 or 500 mL of TWBC. During TWBC delivery, and for 10 minutes after cross-clamp removal, samples were taken from the aorta and coronary sinus to measure the hydrogen ion, lactate, and oxygen content. RESULTS: At the end of TWBC delivery, the 500 mL group had significantly less hydrogen ion washout (p = 0.006) compared with the 250 mL group. Also, more hydrogen ions (p = 0.02) and lactate (p = 0.02) had been washed out during the entire period of TWBC delivery in the 500 mL group compared with the 250 mL, indicating better metabolic recovery. By 4 minutes after aortic cross-clamp removal, hydrogen ion and lactate washout, as well as oxygen extraction was similar in the two groups. However, the time to return to regular mechanical activity was prolonged in the 500 mL group, 5.8 (3) versus 4.6 (3) minutes in the 250 mL group (p = 0.05). Though there was no difference in postoperative Troponin T levels, eight patients in the 500 mL group versus four in the 250 mL group required ionotropic support (p = 0.1). CONCLUSIONS: A total of 500 mL of hotshot achieves a better metabolic state after hotshot delivery. However, there is no clinical benefit or improvement in the postoperative Troponin T release suggesting that in a short ischemic time, 500 mL TWCB has a limited clinical benefit.