Regression of cardiac hypertrophy by 1,4 dihydropyridines in hypertensive patients

BACKGROUND: Left ventricular hypertrophy (LVH) represents an important intermediate end-point for, for example, the progression to heart failure. The persistence or progression of LVH despite antihypertensive therapy probably reflects the persistence or activation of mechanisms that negatively affect the cardiovascular system and, consequently, long-term outcome. EFFECT OF MODERN ANTIHYPERTENSIVE AGENTS: Long-term treatment with rapid-onset (and usually short-acting) dihydropyridine calcium antagonists is significantly less effective than angiotensin converting enzyme (ACE) inhibition in reducing left ventricular mass (LVM) in hypertensive patients. Both intermittent, and probably only partial, blood pressure control and an increase in sympathetic activity resulting from rapid decreases in blood pressure following dosing with such calcium antagonists may contribute to this relative ineffectiveness. In contrast, more recent studies have demonstrated that the longer acting dihydropyridines can reduce LVM as effectively as ACE inhibitors. DISTINCTIONS AMONG DIHYDROPYRIDINE CALCIUM ANTAGONISTS: Among the 1,4-dihydropyridines, drugs such as amlodipine and nifedipine in the gastrointestinal therapeutic system (GITS) maintain good blood pressure control over the full 24-h dosing period and do not cause dose-related increases in sympathetic activity. In contrast, extended-release felodipine has been shown to provide only intermittent blood pressure control, still leading to sympathetic activation. Notably, during short periods of noncompliance, blood pressure control is maintained with intrinsically long-acting agents such as amlodipine but not with slow-release formulations of short-acting agents such as nifedipine GITS. CONCLUSIONS: It is possible that the rate of onset and duration of action of various dihydropyridines may be pivotal factors in determining their effects on cardiovascular outcomes. Thus, the least beneficial dihydropyridines may be rapid-onset, short-acting agents, such as nifedipine capsules, and the most beneficial may be the slow-onset, long-acting agents such as amlodipine.     

From noxiustoxin to Shiva-3, a peptide toxic to the sporogonic development of Plasmodium berghei

This communication reviews shortly the main structural and functional characteristics of Noxiustoxin, a 39 amino acid residue peptide, maintained closely packed by three-disulfide bridges and its effects on excitable membranes. Shiva-3, a cecropin like-peptide composed of 38 amino acid residues is also briefly reviewed. Its design and synthesis was made possible by the expertise gained through the work previously performed with Noxiustoxin. One of the most prominent functional characteristics of Shiva-3 is the toxic effect upon the sporogonic development of Plasmodium berghei (responsible for a murine version of malaria). A synthetic Shiva-3 gene was constructed by recursive polymerase-chain reaction (PCR) methodology and expressed using the vector pGEX2T as a hybrid protein between the glutathione-S-transferase at the N-terminal and Shiva-3 in the C-terminal part of the hybrid. The recombinant protein kills bacteria and Plasmodium berghei. The future aim of this work is to produce a transgenic mosquito that carries the message for synthesis and excretion of Shiva-3 and similar peptides, in the midgut of mosquitoes, in an attempt to control the spreading of human malaria.     

Effect of morphine-diazepam on signs of anesthesia, awareness, and dreams of patients under N2O for cesarean section

Morphine (0.2 mg/kg) and diazepam (0.1 mg/kg) were injected IV after delivery of the fetus in 68 parturients undergoing cesarean section (CS). General anesthesia was with thiamylal-N2O-O2 (4:2) and muscle relaxant. Twenty-four to 36 hours postoperatively, 1 patient had recall, 1 had unpleasant dreams, and 2 had pleasant dreams. The incidence of recall and unpleasant dreams was 3.8 percent in elective CS and 0 percent in emergency cesareans. Morphine-diazepam combination caused anterograde and retrograde amnesia. During the cesarean, movement of patient, size of pupils, or changes in blood pressure were not indicative of awareness or dreams. During anesthesia, 33 percent O2 produced adequate oxygenation of mother and fetus.     

Effect of water of hydration on the measurement of the protein efficiency ratio of casein and soybean protein with rats

The hydration of soybean protein or casein prior to mixing of the diet improves the apparent protein efficiency ratio (PER). The PER of soybean protein was improved more than that of casein, so that an increase in adjusted PER of soybean protein was observed also. The improvement did not appear to be associated with digestibility. It is theorized that some diets with dry protein isolates may be less acceptable to the rat due to the dusty nature of the isolate. Consequently, diets with such isolates may have a lower PER. The effect can be overcome by hydrating the protein isolates prior to mixing the diet.     

Image processing based on the combination of high-resolution electron microscopy and electron diffraction

A method of crystal structure determination by electron crystallographic image processing based on the combination of high-resolution electron microscopy (HREM) and electron diffraction is introduced. It consists of two stages: image deconvolution and resolution enhancement. In the first stage an image taken at an arbitrary defocus condition is transformed into the structure image with the resolution depending on the resolution of the electron microscope. In the second stage the image resolution is enhanced to the diffraction resolution limit by combining the electron diffraction data and using the phase extension technique so that in the final image most unoverlapped atoms can be resolved individually. The experimental diffraction intensities are corrected for approximating to square structure factors. The principle of the image processing and the procedure of diffraction intensity correction are briefly described and the results of applications are illustrated. Since the method is based on the weak phase object approximation (WPOA), the validity of WPOA is discussed by introducing an approximate image contrast theory named pseudo weak phase object approximation (PWPOA) to demonstrate the image contrast change with the crystal thickness for very thin crystals.