Design of an intravenous oxygenator

The aim of this study was to design a new intravenous blood–gas exchange device and to estimate the design characteristics of the device with a dimensionless function by using a substance that can be used instead of bovine blood. In addition, the characteristics of oxygen transfer were estimated using empirical formulas and the reliability of the equations was ascertained by comparing their output with an experiment performed using bovine blood. The dimensionless function was derived using distilled water and bovine blood to estimate the oxygen transfer rate. Using the derived equations, the calculated oxygen transfer rates for bovine blood and distilled water were similar for Reynolds numbers ranging from 0.7 to 7.0. Therefore, it is possible to estimate the oxygen transfer rate in bovine blood, which is a non-Newtonian fluid, using distilled water, which is a Newtonian fluid. Moreover, it was possible to verify the related equations because the oxygen transfer rate could be estimated using the derived equations, according to the diameters of the various device modules.     

The in vitro pharmacological profile of KR31080, a nonpeptide AT1 receptor antagonist

Summary— KR31080 (2-butyl-5-methyl-6-(1-oxopyridin-2-yl)-3-[[2'-(1H-tetrazol-5-yl) biphenyl-4-yl]methyl]-3H-imidazo[4,5-b] pyridine) is a potent inhibitor of angiotensin type 1 (AT₁) receptors in rabbit aorta and human recombinant AT₁ receptors. In the isolated rabbit thoracic aorta, KR31080 caused a nonparallel shift to the right of the concentration-response curves to angiotensin II (All) with decreased maximal response (pD'₂ = 10.1 ± 0.1), but had no effect on the contractile response induced by norepinephrine. KR31080 inhibited specific [¹²⁵I]AII binding to rabbit aortic membranes (AT, receptors) and [¹²⁵I][Sar¹, Ile⁸]AII binding to human recombinant AT₁ receptors in a concentration-dependent manner with IC₅₀ values of 0.84 ± 0.08 nM and 1.92 ± 0.15 nM, respectively, but did not inhibit specific [¹²⁵I)AII binding to bovine cerebellum membranes (ÀT₂ receptors). In the Scatchard analysis, KR31080 interacted with rabbit aortic AT₁ receptors in a competitive manner, similar to losartan. These results demonstrate that KR31080 is a potent and AT₁ selective angiotensin receptor antagonist which exerts a competitive antagonism in the [¹²⁵I]AII binding assay and insurmountable AT₁ receptor antagonism in the functional study.     

Transneuronal degeneration of thalamic neurons following deafferentation: quantitative studies using [3H]thymidine autoradiography.

Transneuronal degeneration of thalamic neurons following partial deafferentation was studied using [3H]thymidine autoradiography. Timed-pregnant female Sprague-Dawley rats received systemic injections of [3H]thymidine on embryonic day (E) 13, 14 and/or 15. On the day of birth, pups were anesthetized by hypothermia and subjected to unilateral enucleation, unilateral removal of the inferior colliculus or sham lesion. Animals were sacrificed on postnatal day 10 or 30 and the brains processed for autoradiography. Material from sham-lesioned animals demonstrates that neurons destined for the dorsal lateral geniculate nucleus (LGd) undergo final mitoses on E13, 14 and 15. Neurons in the ventral medial geniculate nucleus (MGv) undergo final mitoses on E13 and 14. Thirty days following neonatal unilateral eye removal, the contralateral LGd displays a loss of approximately 30-35% of [3H]thymidine labeled neurons. Neonatal unilateral removal of the inferior colliculus results in a loss of approximately 30-40% of labeled neurons in MGv. For both LGd and MGv, shorter survival times reveal less severe cell loss. Late generated (E15) LGd neurons show less severe loss following enucleation than do earlier generated neurons. These results document the degree of cell loss in sensory thalamic nuclei following deafferentation and demonstrate that [3H]thymidine autoradiography provides a useful quantitative method for assessing anterograde transneuronal cell loss in targeted populations of neurons in the developing central nervous system.     

Food deprivation and hypothalamic neuropeptide gene expression: effects of strain background and the diabetes mutation.

We have used a novel method to identify genes expressed in the hypothalamus which may be potentially involved in controlling food intake and energy metabolism. We assumed that food deprivation, a powerful stimulus of food intake, would stimulate the activity of neural pathways involved in feeding behavior which should be reflected in an increase in the synthesis of any relevant neuropeptide and its messenger RNA. A study of 5 neuropeptides in 5 strains of mice has identified neuropeptide Y (NPY) as a gene whose expression in the hypothalamus is controlled by nutritional status, suggesting that hypothalamic NPY neurons are a link in the neural network regulating feeding behavior and energy metabolism. In addition, we have studied the effect of the diabetes mutation on neuropeptide gene expression during fasting and refeeding. Our findings suggest that abnormal NPY and enkephalin gene expression in the hypothalamus may be two important determinants of the expression of the diabetes mutation.     

Glutamate receptor antagonists block cocaine-induced convulsions and death.

The involvement of excitatory amino acid (EAA) receptors in mediation of the toxic effects of cocaine was studied in male ICR mice. Cocaine HCl (90 mg/kg, IP) induced seizures in 95% and death within 24 h in 68% (n = 135) of the animals. There was a significant correlation (r = .54) between the time to onset of convulsions and the time to death in mice which died within 30 min of injection (n = 84). Pretreatment with selected EAA receptor antagonists 15 min prior to cocaine differentially blocked cocaine toxicity. Selective N-methyl-D-aspartic acid (NMDA) receptor antagonists (MK-801, dextrorphan, CPP) decreased both the incidence of seizures and mortality. A nonselective EAA antagonist, kynurenic acid, decreased lethality in doses which did not reduce convulsions. A similar action was observed following pretreatment with the selective kainic acid/AMPA receptor antagonist, GDEE. Antagonists at EAA receptors can provide significant protection against cocaine-induced toxicity. Moreover, the data provide evidence for the involvement of both NMDA and non-NMDA receptor subtypes in aspects of cocaine toxicity.     

Correlation of perinatal brain growth with age, body size, sex, and race

This study compares the weight of the human brain to gestational age and body dimensions. A new formula for calculating the rate of growth is proposed. It consists of a second order polynomial function: Y = A0 + A1X + A2X2, in which Y is brain weight, body weight, height, or body surface area; X is gestational age in weeks and A0, A1, and A2 are statistically estimated coefficients. In utero, the growth rate is most rapid for body weight, followed in decreasing order by brain weight, body surface area, and height. Brain growth is the same for both sexes in black and white races; it accelerates between the 20th and 45th weeks of gestation. The size of the newborn infant brain is directly related to gestational age and body size and is not determined by sex or race.     

Central venous catheter-related Rhodotorula rubra fungemia

With the increased use of indwelling central venous catheters, increasing numbers of cases of Rhodotorula fungemia have been observed in patients with neoplasia and neutropenia. In most patients with catheter-related Rhodotorula fungemia, the condition has been treated with broadspectrum antibiotics. We report two cases of central venous catheter-related Rhodotorula rubra fungemia that occurred in patients with acute myeloblastic leukemia. Both patients were in a state of neutropenia. One patient was treated with amphotericin B and his central venous catheter was removed, but he died of Klebsiella pneumoniae bacteremia. The other patient was treated with amphotericin B and discharged, with a central venous catheter, after recovery from neutropenia. Although the management of catheter-related Rhodotorula fungemia infections remains controversial, resolution of the underlying disease is more important than catheter removal for recovery from Rhodotorula rubra fungemia. Received: August 22, 2001 / Accepted: October 8, 2001     

Outflow of aqueous humor following cyclodialysis or ciliochoroidal detachment in rabbit

Cyclodialysis and ciliochoroidal detachment were performed in three eyes of three rabbits and in three eyes of another three rabbits, respectively. After aspiration of the aqueous humor, 0.1 ml of 10% sodium fluorescein was injected intracamerally, and the eyeball was enucleated between 30 minutes and one hour after injection and prepared for fluorescence microscopy. Sodium fluorescein concentrations in the supraciliary space were much greater in the group with cyclodialysis or ciliochoroidal detachment than in the normal control group. These results suggest that (1) in the eye with cyclodialysis, the aqueous humor may freely gain access to the supraciliary space through the cleft between the anterior chamber and the supraciliary space and then be removed rapidly and (2) in the eye with ciliochoroidal detachment, the aqueous humor may pass through the uveoscleral outflow pathway.