Magnetic resonance imaging of brain abnormalities in patients with the Nijmegen breakage syndrome

The results of brain MRI are presented in 22 patients with documented Nijmegen breakage syndrome (NBS), aged from 1 and 9/12 to 20 years. T1-, PD or FLAIR and T2-weighted SE/TSE images in three planes were obtained. Twenty-one patients showed microcephaly. Decreased size of frontal lobes and narrow frontal horns of the lateral ventricles was observed in all cases. In 6 patients agenesis of the posterior part of the corpus callosum was found as well as colpocephaly and temporal horn dilatation. In 2 patients callosal hypoplasia was accompanied by other anomalies: abnormal cerebrospinal fluid spaces. Sinusitis was present in all patients as a result of primary immunodeficiency. As in ataxia teleangiectasia and other breakage syndromes, NBS patients show inherited malignancy susceptibility and hypersensitivity to X and gamma radiation. Because of that computed tomography is contraindicated in these patients and MRI should be the method of choice in diagnostic imaging.     

Effects of active recovery on power output during repeated maximal sprint cycling

The effects of active recovery on metabolic and cardiorespiratory responses and power output were examined during repeated sprints. Male subjects (n = 13) performed two maximal 30-s cycle ergometer sprints, 4 min apart, on two separate occasions with either an active [cycling at 40 (1)% of maximal oxygen uptake; mean (SEM)] or passive recovery. Active recovery resulted in a significantly higher mean power output ( ) during sprint 2, compared with passive recovery [ ] 603 (17) W and 589 (15) W, P < 0.05]. This improvement was totally attributed to a 3.1 (1.0)% higher power generation during the initial 10 s of sprint 2 following the active recovery (P < 0.05), since power output during the last 20 s sprint 2 was the same after both recoveries. Despite the higher power output during sprint 2 after active recovery, no differences were observed between conditions in venous blood lactate and pH, but peak plasma ammonia was significantly higher in the active recovery condition [205 (23) vs 170 (20) μmol · 1⁻¹;P < 0.05]. No differences were found between active and passive recovery in terms of changes in plasma volume or arterial blood pressure throughout the test. However, heart rate between the two 30-s sprints and oxygen uptake during the second sprint were higher for the active compared with passive recovery [148 (3) vs 130 (4) beats · min⁻¹;P < 0.01) and 3.3 (0.1) vs 2.8 (0.1) 1 · min⁻¹;P < 0.01]. These data suggest that recovery of power output during repeated sprint exercise is enhanced when low-intensity exercise is performed between sprints. The beneficial effects of an active recovery are possibly mediated by an increased blood flow to the previously exercised muscle.     

The measurement of the tacticity of poly(vinyl chloride) by 13C nuclear magnetic resonance spectroscopy

Fourier transform ¹H-decoupled ¹³C NMR spectra were obtained on seven poly(vinyl chloride), (PVC), samples in solution in o-dichlorobenzene. Four of the polymers were of the commercial type and the others were prepared by suspension polymerisation at +90°C, +5°C, and -30°C. Measurements of the spectra were used to assess the precision and accuracy with which information about the tacticity of PVC can be obtained from such spectra. The results show that the well-resolved α-carbon triad and β-carbon tetrad spectra obtained may be reliably analysed to give values of the probability of syndiotactic placement with a precision of about 0,005 for measurements on a single run on a single sample. The simplest and probably the most reliable method of measuring the areas under the peaks which correspond to specific triads ot tetrads is to use the spectrometer integrator, although results of slightly lower precision may be obtained by the use of a curve resolver. Consideration of possible systematic errors due to different T₁ relaxation times, unequal nuclear Overhauser enhancement (NOE) factors, and incomplete dissolution of the polymer has shown that the only one of these which is possibly significant is that due to NOE, which is almost certainly less than 0,008, so that the absolute accuracies of the P_r values should be better than that. A more detailed study of the data shows that the polymers made at 5°C and -30°C are almost certainly non-Bernoullian and that firstoder Markov statistics can adequately describe the observed departures from Bernoullian statistics. These departures may have significant consequences for the physical properties of the polymers.     

Induction of chromosmal aberrations in the syrian hamster by insecticides tested in vivo

The insecticides demeton, dimetoat, dichlorovos, endosulfan, trichlorofon, carbaryl, lindane, methoxychlor, propoxur and malathion were examined for their ability to induce chromosomal aberrations in the bone marrow cells of the Syrian hamster (Mesocricetus auratus) treated in vivo. Mutagenicity of commercial preparations was examined at four doses: LD₅₀; 1/2, 1/5 and 1/10 LD₅₀. The positive control was an IP injection of cyclophosphamide to hamsters at a dose of 40 mg/kg body wt. Demeton, dichlorovos and endosulfan gave positive results. Malathion, dimethoate and the mixture of methoxychlor and propoxur were weakly clastogenic; at some doses these compounds induced statistically significant increases in the number of aberrations. Trichlorfon and the mixture of carbaryl and lindane were negative in this test.This work was supported by the Polish Academy of Sciences within the projet 09.7.3.4.3     

Hypertension two years after renal transplantation: causes and consequences

The incidence of hypertension 2 years after renal transplantation and the possible causes of hypertension were studied retrospectively. A group of 93 patients treated with cyclosporin (CyA), azathioprine (Aza), and/or prednisolone (Pred) were compared to a group of 31 patients treated with Aza and Pred. There were more patients with hypertension in the CyA group (73%) than in the Aza group (58%). Hypertension before transplantation predisposed to hypertension after transplantation. After transplantation, hypertension was most common among patients with polycystic kidney disease (46%), chronic glomerulonephritis (67%), and diabetes (71%). The accumulated immunosuppressive medication (CyA/Pred) did not affect the occurrence of hypertension. Hypertensive patients had significantly poorer graft function than did normotensive patients (serum creatinine level 229 mol/l vs 162 mol/l, P<0.01). The 10-year graft survival was markedly impaired in the group with hypertension (42% vs 65% for normotensives, P<0.05). The 10-year patient survival was 59% vs 79% (P=NS). The study further confirms the frequent finding that hypertension has a negative effect on graft and patient survival rates.     

Increased susceptibility of aged rats to hepatocarcinogenesis by the peroxisome proliferator nafenopin and the possible involvement of altered liver foci occurring spontaneously

We investigated the mechanism of the hepatocarcinogenic action of nafenopin (NAF), a nongenotoxic peroxisome proliferator. Groups of male rats aged 13 wk (designated "young") or 57 wk (designated "old") were fed NAF for 13 mo; additional groups received a basal diet or a phenobarbital (PB)-containing diet as positive control. The following results were obtained. (a) NAF produced numerous hepatocellular adenomas and carcinomas in old animals but very few in young animals. A similar result, although less pronounced, was seen with PB. Adenomas of PB-treated groups mostly consisted of eosinophilic and glycogen-storing cells. However, adenomas and carcinomas of NAF-treated livers were composed of weakly basophilic cells. (b) Phenotypically altered foci, evaluated in hematoxylin:eosin-stained sections, appeared spontaneously in untreated livers. The majority of these foci was either of the eosinophilic-clear cell or the tigroid cell type. In addition, we identified foci which are characterized by weak, diffuse cytoplasmatic basophilia. Their phenotype was similar to that of adenomas and carcinomas in NAF-treated rats. The number and size of eosinophilic-clear cell and of tigroid cell foci increased considerably with the age of the animals. At the end of the experiment, approximately 2.4% of liver tissue was occupied by focal cells. NAF, but not PB, treatment led to a selective increase in number and size of weakly basophilic foci. This subtype has previously been described as a likely precursor lesion for liver tumors induced by an aflatoxin B1-NAF initiation-promotion regimen (B. Kraupp-Grasl et al., Cancer Res., 50:3701-3708, 1990). These findings suggest that the peroxisome proliferator NAF leads to tumor development in aging rat liver by promotion of spontaneously occurring preneoplastic lesions. The type of lesion appears to be different from that promotable by PB.     

Effects of lead,copper, and zinc on the rat's lactate dehydrogenase in vivo and in vitro

Following subacute intoxication of rats with Pb-, Cu-, and Zn-salts (separately or in mixture) for 5 weeks, the chelating agent D-penicillamine was administered for 3 weeks. In the course of the 3-month experiment, lactate dehydrogenase (LDH) was estimated in serum and in cytoplasmic fraction of the kidney. Pb²⁺ treatment resulted in an increase of LDH activity, Cu²⁺ in a slight decrease, whereas Zn²⁺ had no effect, respectively. Mixture of these metals caused a significant rise in the enzymatic activity. Seven weeks after the stoppage of the administration of toxic substances, altered LDH activity, both in serum and in kidney returned to normal. D-penicillamine treatment was found to accelerate a restoration of the enzyme activity.In the experiments in vitro, Cu²⁺ inhibited significantly the kidney LDH activity, Pb²⁺ and Zn²⁺ being 100- and 400-times less efficient, respectively. Cu²⁺ inhibition was reversed by D-penicillamine, whereas inhibition of LDH by Zn²⁺ or Pb²⁺ was irreversible.     

Dietary oligofructose lessens hepatic steatosis, but does not prevent hypertriglyceridemia in obese zucker rats

We studied the influence of oligofructose (OFS), a nondigestible fructan, on lipid metabolism in obese fa/fa Zucker rats. The addition of 10 g/100 g OFS to the diet slowed the increase in body weight without modifying serum triglycerides or glucose concentrations after 7 wk of treatment. However, an oral load of 2 g glucose and 5 g corn oil/kg body weight increased triglyceridemia more in OFS-fed rats than in control rats. After 10 wk, OFS decreased the hepatic concentration of triglycerides 57% relative to controls. The less severe steatosis was confirmed by histologic analysis. Among the key enzymes involved in fatty acid synthesis and esterification, only malic enzyme activity was significantly lower in OFS-fed rats than in controls. The epididymal fat mass was significantly lower in OFS-fed rats. In conclusion, dietary enrichment with OFS can counteract both the fat mass development and the hepatic steatosis that occur in obese Zucker rats. Future studies will be designed to clarify in obese animals the influence of dietary OFS on postprandial triglyceridemia, which is an important variable associated with the development of atherosclerosis in humans, and to analyze the biochemical mechanism underlying the "hepatoprotective" effect of OFS.