Asymmetric cell division

With the recent identification of intrinsic cell-fate determinants for asymmetric cell division in several systems, biologists have begun to gain insight into the cellular mechanisms by which these determinants are preferentially segregated into one of the two daughter cells during mitosis so that the daughter cells acquire different fates.     

Sedative and anticonvulsive effects of differently processed rhizoma Pinelliae

Mice were employed to study the sedative and anticonvulsive effects of Rhizoma Pinelliae processed by different methods. The results showed that of raw Rhizoma Pinelliae and its infusion were equally sedative and had anticonvulsive effect against the convulsion caused by cardiazol, but no anticonvulsion effect against that caused by strychnine.     

Variable cerebral responses to equally distinct deviance in four auditory dimensions: a mismatch negativity study

This paper uses regression models to investigate the efficacy of the seat belt regulation as well as the circuit training and testing system in reducing traffic related fatalities in Singapore. The effectiveness of alcohol breathalysers was also studied. Results suggest that the seat belt regulation does not have any impact on traffic fatalities. The use of breathalysers was found to be effective in reducing occupant fatalities. The circuit training and testing system, which aims to equip new pools of motorists with appropriate driving or riding skills, was found to be effective in reducing non-occupant fatalities and total fatalities.     

Apparent thermodynamic parameters of ligand binding to the cloned rat mu-opioid receptor

This study examined the involvement of spinal dopamine D2 receptors in the cardiovascular effects induced by intravenous administration of the selective dopamine D2 receptor agonist quinpirole, as has been previously reported for the hypotensive action of systemic bromocriptine. In normotensive pentobartitone-anaesthetised rats, intravenous injection of quinpirole (25 to 1000 microg/kg) decreased mean aortic pressure and heart rate in a dose-related manner. The intravenous (0.5 mg/kg) or intrathecal (40 microg/rat at T9-T10) pretreatment with domperidone, a dopamine D2 receptor antagonist that does not cross the blood-brain barrier, significantly reduced the maximal hypotensive and bradycardic responses to intravenous quinpirole (1000 microg/kg). In contrast, the latter effects were fully abolished either by intravenous metoclopramide (5 mg/kg) or combined pretreatment with intravenous and intrathecal domperidone. In addition, when injected intrathecally at the T9-T10 level of the spinal cord, quinpirole (7.7 to 61.4 microg/rat) also produced dose-dependent depressor and bradycardic effects which could be blocked by intrathecal, but not intravenous, domperidone pretreatment. This suggests that, in anaesthetised normotensive rats, the hypotensive and bradycardic responses to intravenous quinpirole are fully mediated by dopamine D2 receptors, some of which are located in the peripheral circulation and some of which are located within the spinal cord. The latter finding is novel, suggesting that partial spinal mediation may not be peculiar to bromocriptine, as was previously thought. Rather, partial spinal mediation may be common to most dopamine D2 receptor agonists.     

Possibility of postnatal left ventricular growth in selected infants with non-apex-forming left ventricles

To evaluate postnatal left ventricular growth potential, we reviewed the echocardiograms of seven infants with left ventricles that did not form an apex. Prostaglandins were used to maintain patency of the ductus arteriosus in six infants. Associated abnormalities included aortic stenosis in five, coarctation in three, and left atrial isomerism in one. Initial echocardiographic measurements (7 +/- 9 days) were compared with measurements at 1 month (36 +/- 9 days). Weight (3.0 +/- 0.1 vs 3.0 +/- 0.5 kg) and body surface area (BSA) (0.2 +/- 0.01 vs 0.2 +/- 0.01 m2) did not change. Comparing initial measurements with measurements at 1 month, there were significant increases (p < 0.05) in aortic annulus diameter (4.5 +/- 0.5 vs 5.6 +/- 0.7 mm), aortic root diameter indexed to BSA (2.9 +/- 0.5 vs 3.7 +/- 0.7 cm/m2), ratio of the long axis of the left ventricle to the long axis of the heart (0.74 +/- 0.1 vs 0.86 +/- 0.1), left ventricular end-diastolic volume indexed to BSA (10 +/- 2 vs 24 +/- 9 ml/m2), left ventricular mass indexed to BSA (27 +/- 13 vs 47 +/- 28 gm/m2), mitral valve area indexed to BSA (2.3 +/- 0.5 vs 3.2 +/- 0.7 cm2/m2), left ventricular area (2.1 +/- 0.5 vs 3.6 +/- 1.1 cm2), and Rhodes score (-2.7 +/- 0.5 vs -1.1 +/- 0.9). Tricuspid valve area indexed to BSA (5.8 +/- 1.5 vs 6.1 +/- 1.1 cm2/m2) and long axis of the heart indexed to BSA (13.0 +/- 2.8 vs 13.6 +/- 2.9 cm/m2) did not change. The increase in measurements appeared adequate for biventricular physiology in five infants (four are alive [3.9 +/- 2.6 years] and one died after not being able to wean from the ventilator). These data suggest that a non-apex-forming left ventricle may have postnatal growth potential.     

Calreticulin, a potential vascular regulatory protein, reduces intimal hyperplasia after arterial injury

Both thrombotic and inflammatory responses to arterial injury have been implicated in atherosclerotic plaque growth. Calreticulin is a ubiquitous calcium-binding protein with antithrombotic activity and, in addition, is associated with leukocyte activation. We are investigating calreticulin as a potential vascular regulatory protein. The development of intimal hyperplasia was studied at sites of balloon injury in iliofemoral arteries from 91 rats. Calreticulin was infused directly into the artery immediately before balloon injury, and plaque growth was then assessed at 4 weeks' follow-up. Parallel studies of the effects of each calreticulin domain as well as a related calcium-binding protein, calsequestrin, were examined. The effects of calreticulin on platelet activation, clot formation, and mononuclear cell migration were also studied. When infused before balloon injury in rat iliofemoral arteries, calreticulin, or its high-capacity Ca(2+)-binding C domain, significantly reduces plaque development, whereas calsequestrin, a related calcium-binding protein that lacks the multifunctional nature of calreticulin, does not decrease plaque area (saline: 0.037 +/- 0.007 mm2, calsequestrin: 0.042 +/- 0.021 mm2, calreticulin: 0.003 +/- 0.002 mm2, n = 46, P < .04). The N domain and more specifically the P domain, a low-capacity, high-affinity calcium-binding domain in calreticulin, do not reduce intimal hyperplasia (N + P domain: 0.038 +/- 0.012 mm2, C domain: 0.003 +/- 0.002 mm2, n = 45 rats, P < .0001). Calreticulin reduces macrophage and T cell staining in the arterial wall after injury but has no direct effect on monocyte migration in vitro (percent medial area staining positive for macrophage 24 hours after injury (N + P: 4.06 +/- 1.42, calreticulin: 0.273 +/- 0.02; n = 26, P < .009). Calreticulin does, however, reduce platelet-dependent whole blood clotting time, in vitro (baseline: 78.23 +/- 2.04 seconds, calreticulin: 113.5 +/- 1.95 seconds; n = 5, P < .002). We conclude that calreticulin significantly reduces intimal hyperplasia after arterial injury, potentially acting as a vascular regulatory protein.     

Evaluation of CI-973, a platinum analogue, in refractory or relapsed acute leukemia

Uranium isotopes were given via single intravenous injection into 22 young adult beagle dogs of both sexes to determine the metabolism of this element. Animals were given either 232U, 233U, 238U, or a combination of 232 (+) 233U. Calculations to assign a value of skeletal dose for each dog were performed using published radioactive properties of each uranium isotope and the metabolic data (including measured retention and skeletal distribution) derived from this study during a period of up to 2 y after injection. We believe that the procedures illustrated in this communication can serve as a useful pattern for estimating skeletal radiation doses to humans contaminated with 232U, 233U, or 238U.     

An epidemiological investigation of eperythrozoon infection in human and animals (II)

This is the second of two studies done to determine whether moderate Gz exposure facilitates back disability. Cumulative trauma (repeated moderate to high G) exposures could be a precipitant of back pain in the military population. There is at present no reliable method of predicting who will suffer from back pain. We looked at officer back disability rates at separation from the Air Force (1972-1993). We compared non-rated Air Force officers to pilots and navigators exposed to low G and moderate to high G. We found no significant differences between aircrew and non-aircrew individuals until 1985, when the rates for aircrew fell below those of non-rated officers. Moderate G exposure does not seem to be a predictor of subsequent back disability. We recommend a larger prospective study of all rated and non-rated officers. We recommend that each separating officer undergo a detailed physical examination and answer a detailed back questionnaire.