Transplacental IgG Subclass Concentrations in Pregnancies at Risk of Haemolytic Disease of the Newborn

The relationship of haemolytic disease of the newborn (HDN) to the transplacental passage of the four IgG subclasses was assessed at varous gestational ages by comparing the maternal and fetal IgG subclass concentrations in 34 pregnancies at risk of HDN with those in 30 pregnancies not at risk. Higher maternal and fetal IgG1 levels were attained in pregnancies at risk of HDN than in pregnancies not at risk. In contrast, a slight decrease in maternal IgG2 and IgG4 levels occurred in pregnancies at risk of HDN, as compared with a slight rise in maternal IgG2 and IgG4 levels in pregnancies not at risk of HDN. Changes in fetal IgG2 and 4 concentrations in either type of pregnancy were very similar, showing only slight increases between the 19th and 34th week of gestation. A slight decrease in maternal IgG3 occurred in both types of pregnancy. In contrast, higher and fairly steady levels of fetal IgG3 were observed in fetuses not at risk of HDN throughout gestation, when compared with those in 'at risk' pregnancies. However, the statistical reliability of these results is not clear since only small numbers of samples were tested and because wide variations in IgG concentrations were observed. The IgG subclass concentrations in 50 paired maternal and cord blood samples were also measured and revealed that IgG1 levels were substantially higher in cord rather than maternal blood; cord and maternal IgG2, 3 and 4 levels, on the other hand, were fairly similar.     

The effects of adenosine on transepithelial resistance and sodium uptake in the inner medullary collecting duct

It has been previously demonstrated that adenosine induces natriuresis when administered directly into the renal circulation of the rat. It was postulated that the mechanism was inhibition of tubule Na⁺ reabsorption. In the current study, the hypothesis was tested that adenosine inhibits ion reabsorption across the inner medullary collecting duct (IMCD), a tubule segment which is rich in adenosine receptors. IMCD epithelium from rat kidney was grown in primary culture as a confluent monolayer on Costar filters, allowing selective access to the basolateral and apical surfaces of the cells. Transepithelial resistance was taken as a measure of epithelial permeability and ion conductance. Na⁺ uptake was studied using ²²Na⁺ and used to determine the permeability of the epithelial monolayer specifically to Na⁺. Exposure of the basolateral aspect of the monolayer to adenosine (10⁻⁸–10⁻⁷ M) increased transepithelial resistance in a dose- and time-dependent manner; in parallel, adenosine (10⁻⁷–10⁻⁶ M) reduced apical Na⁺ uptake from 20±5 to 10±2 nmol/cm². 1,3-Dipropyl-8-(2-amino-4-chlorophenyl)-xanthine (PACPX, 5×10⁻⁹ M), an adenosine antagonist with selectivity for the A₁ receptor, inhibited the rise in transepithelial resistance and the decrease in Na⁺ uptake following the addition of adenosine. The effects of adenosine on transepithelial resistance were reproduced with the A₁ receptor selective adenosine analogue N ⁶-cyclohexyladenosine (CHA, 10⁻⁸ –10⁻⁷ M) but not with the A₂ selective analogues, 5′-N-ethylcarboxamidoadenosine (NECA) or CGS 21680. CHA (10⁻⁷ M) inhibited apical Na⁺ uptake by 50%, an effect abolished by PACPX. The effects of adenosine on transepithelial resistance and Na⁺ uptake were inhibited, but only in part, by amiloride. These data suggest that adenosine inhibits ion movement, specifically apical Na⁺ uptake, across the IMCD epithelium and that this effect is mediated by A₁ receptors from the basolateral aspect of the cell. The results are consistent with the hypothesis that adenosine inhibits Na⁺ reabsorption across the IMCD.     

A benign congenital myopathy in an inbred Samaritan family.

We describe a novel form of myopathy in a mother and her two daughters from an inbred Samaritan family. The patients displayed severe neonatal hypotonia, lethargy and dysmorphic features. Motor milestones were delayed; however, the hypotonia and muscle weakness gradually improved during the first 2 years of life and independent walking was achieved by 18 months. The mother at the age of 23 years shows myopathic facies and minimal proximal weakness. Her intelligence is normal. Her muscle biopsy revealed central nuclei and disruption of the intermyofibrillary network with moth eaten and spiral fibers. Mutations in SMN, MTM1 and the myotonic dystrophy genes were excluded. We suggest this is a new benign form of congenital myopathy. Inheritance is probably autosomal recessive.     

Stability and specificity of heterodimer formation for the coiled‐coil neck regions of the motor proteins Kif3A and Kif3B: the role of unstructured oppositely charged regions

Abstract: We investigated the folding, stability, and specificity of dimerization of the neck regions of the kinesin‐like proteins Kif3A (residues 356–416) and Kif3B (residues 351–411). We showed that the complementary charged regions found in the hinge regions (which directly follow the neck regions) of these proteins do not adopt any secondary structure in solution. We then explored the ability of the complementary charged regions to specify heterodimer formation for the neck region coiled‐coils found in Kif3A and Kif3B. Redox experiments demonstrated that oppositely charged regions specified the formation of a heterodimeric coiled‐coil. Denaturation studies with urea demonstrated that the negatively charged region of Kif3A dramatically destabilized its neck coiled‐coil (urea_1/2 value of 3.9 m compared with 6.7 m for the coiled‐coil alone). By comparison, the placement of a positively charged region C‐terminal to the neck coiled‐coil of Kif3B had little effect on stability (urea_1/2 value of 8.2 m compared with 8.8 m for the coiled‐coil alone). The pairing of complementary charged regions leads to specific heterodimer formation where the stability of the heterodimeric neck coiled‐coil with charged regions had similar stability (urea_1/2 value of 7.8 m ) to the most stable homodimer (Kif3B) with charged regions (urea_1/2 value of 8.0 m ) and dramatically more stable than the Kif3A homodimer with charged regions (urea_1/2, value of 3.9 m ). The heterodimeric coiled‐coil with charged extensions has essentially the same stability as the heterodimeric coiled‐coil on its own (urea_1/2 values of 7.8 and 8.1 m , respectively) suggesting that specificity of heterodimerization is driven by non‐specific attraction of the oppositely unstructured charged regions without affecting stability of the heterodimeric coiled‐coil.     

High performance liquid chromatographic analysis of insulin degradation products from a cultured kidney cell line

The kidney is a major site for insulin removal and degradation, but the subcellular processes and enzymes involved have not been established. We have examined this process by analyzing insulin degradation products by HPLC. Monoiodoinsulin specifically labeled on either the A14 or B26 tyrosine residue was incubated with a cultured kidney epithelial cell line, and both intracellular and extracellular products were examined on HPLC. The products were then compared with products of known structure generated by hepatocytes and the enzyme insulin protease. Intracellular and extracellular products were different, suggesting two different degradative pathways, as previously shown in liver. The extracellular degradation products eluted from HPLC both before and after sulfitolysis similarly with hepatocyte products and products generated by insulin protease. The intracellular products also eluted identically with hepatocyte products. Based on comparisons with identified products, the kidney cell generates two fragments from the A chain of intact insulin, one with a cleavage at A13-A14 and the other at A14-A15. The B chain of intact insulin is cleaved in a number of different sites, resulting in peptides that elute identically with B chain peptides cleaved at B9-B10, B13-B14, B16-B17, B24-B25, and B25-B26. These similarities with hepatocytes and insulin protease suggest that liver and kidney have similar mechanisms for insulin degradation and that insulin protease or a very similar enzyme is involved in both tissues.     

Estradiol concentration in the serum of the one-humped camel (Camelus dromedarius) during the various reproductive stages

During the estrous cycle of the camel the concentration of estradiol (E₂) varies between 9 and 110 pg/ml. In early estrus, the peak level of E₂ (74.7 ± 6.61 pg/ml, n = 11) is maintained for 2.9 ± 1.83 days. The length of an estrous cycle is 17.2 days. In the 10th month of pregnancy the level of E₂ rises abruptly to 338.3 ± 162.42 pg/ml and continues to rise until the 12th month, peaking at 606 ± 120.27 pg/ml. The hormone concentration then drops until the day of parturition (mean 113.4 ± 26.51 pg/ml). The level of E₂ during the nonbreeding season (May–November) is low (6–48 pg/ml).     

Primed polymorphonuclear leukocytes, oxidative stress, and inflammation antecede hypertension in the Sabra rat

Hypertension is accompanied by systemic oxidative stress, inflammation, and priming of peripheral polymorphonuclear leukocytes (PMNLs), yet the involvement of these factors in the pathophysiology of hypertension is incompletely understood. We investigated the relationship between oxidative stress, primed PMNLs, and inflammation and the development of hypertension in the Sabra rat model of salt-sensitive hypertension. Sabra hypertension-resistant rats (SBN/y) (salt-resistant) and Sabra hypertension-prone rats (SBH/y) (salt-sensitive) were studied under normal conditions or during salt loading. Systolic blood pressure (BP) was measured by the tail-cuff method. The extent of oxidative stress was evaluated by the rate of superoxide release from PMNLs, plasma-reduced glutathione (GSH) levels, malondialdehyde (MDA) levels (estimated by thiobarbituric acid-reacting substances), and plasma-carbonylated fibrinogen (Western blotting). Plasma fibrinogen levels and the peripheral PMNL count served as indices of inflammation. In SBH/y and SBN/y provided regular chow without salt loading, BP did not rise above baseline values, yet superoxide release, plasma MDA, carbonylated fibrinogen, and PMNL count were higher in SBH/y than in SBN/y, whereas GSH levels were lower in SBH/y. Four weeks of salt loading resulted in a gradual increase in systolic BP in SBH/y to 205+/-3 mm Hg, whereas BP remained in SBN/y at baseline normotensive levels. All the parameters reflecting oxidative stress and inflammation were further aggravated with the development of hypertension in salt-loaded SBH/y. We conclude that primed PMNLs, oxidative stress, and inflammation antecede the development of hypertension in this experimental model of hypertension.     

Feasibility of using post-contrast dual-energy CT for pediatric radiation treatment planning and dose calculation

Objectives:When iodinated contrast is administered during CT simulation, standard practice requires a separate non-contrast CT for dose calculation. The objective of this study is to validate our hypothesis that since iodine affects Hounsfield units (HUs) more than electron density (ED), the information from post-contrast dual-layer CT (DLCT) would be sufficient for accurate dose calculation for both photon and proton therapy.Methods and materials:10 pediatric patients with abdominal tumors underwent DLCT scans before and after iodinated contrast administration for radiotherapy planning. Dose distributions with these DLCT-based methods were compared to those with conventional calibration-curve methods that map HU images to ED and stopping-power ratio (SPR) images.Results:For photon plans, conventional and DLCT approaches based on post-contrast scans underestimated the PTV D99 by 0.87 ± 0.70% (p = 0.18) and 0.36 ± 0.31% (p = 0.34), respectively, comparing to their non-contrast optimization plans. Renal iodine concentration was weakly associated with D99 deviation for both conventional (R² = 0.10) and DLCT (R² = 0.02) approaches. For proton plans, the clinical target volume D99 errors were 3.67 ± 2.43% (p = 0.0001) and 0.30 ± 0.25% (p = 0.40) for conventional and DLCT approaches, respectively. The proton beam range changed noticeably with the conventional approach. Renal iodine concentration was highly associated with D99 deviation for the conventional approach (R² = 0.83) but not for DLCT (R² = 0.007).Conclusion:Conventional CT with iodine contrast resulted in a large dosimetric error for proton therapy, compared to true non-contrast plans, but the error was less for photon therapy. These errors can be greatly reduced in the case of the proton plans if DLCT is used, raising the possibility of using only a single post-contrast CT for radiotherapy dose calculation, thus reducing the time and imaging dose required.Advances in knowledge:This study is the first to compare directly the differences in the calculated dose distributions between pre- and post-contrast CT images generated by single-energy CT and dual-energy CT methods for photon and proton therapy.