Advances in solid alanine radiolysis understanding

To better understand the composite character of irradiated alanine ESR spectra, a comparative study of few simple amino acids is performed in order to identify the different radio-induced radicals and their proportions. A dedicated spin-trapping method coupled with High Performance Liquid Chromatography (HPLC) is developed and carried out on irradiated alanine, glycine and valine; labeled or not. This study leads us to obtain different isolated trapped radical spectra where hyperfine coupling constants could be evaluated. For alanine, only two species are identified with relative proportions around 97 and 3% in contradiction with recent published articles. The main species has a particularity on its hyperfine coupling constants when labeled carbons are used. Very high hyperfine coupling constants are observed with the carboxylic acid function carbon for the three studied amino acid.

Treatment with adefovir dipivoxil in a renal transplant patient with renal insufficiency and lamivudine-resistant hepatitis B infection

Lamivudine is a safe, effective treatment for hepatitis B virus (HBV) reactivation after renal transplantation. However, prolonged lamivudine therapy can produce resistance to the drug. Adefovir dipivoxil (ADV) has demonstrated efficacy in patients with lamivudine resistance, but there is limited clinical experience in patients with either renal transplants or severe renal insufficiency. A 47-year-old man with asymptomatic HBV infection underwent renal transplantation in November 1995. In September 2000 lamivudine therapy was initiated to treat HBV reactivation. The outcome was good, with negative HBV DNA levels. Two years later, significant viral replication developed again. At that time the patient already had advanced renal insufficiency due to chronic graft nephropathy. The transaminase levels were increased, and the HBV DNA reached greater than 200,000 copies/mL by polymerase chain reaction, with development of ascites and cirrhosis. The patient was started on ADV 10 mg every 72 hours (dose adjusted to renal function). There was rapid normalization of hepatic enzymes and progressive decline of the viral load. HBV DNA became negative after 6 months of ADV treatment. The renal function has since remained stable. This case suggests that ADV can be safe and effective in the treatment of renal transplant patients with lamivudine-resistant hepatitis B, even in the presence of advanced renal insufficiency.

Effect of Parathyroidectomy on Renal Graft Function

Some authors have reported acute impairment of renal transplant function after parathyroidectomy (PTx). Since 1996 PTx has been performed in 22 renal transplant recipients (follow-up, 24.2 +/- 15 months; serum creatinine concentration (SCr) pre-PTx, 1.26 +/- 0.4 mg/dL). We analyzed the serum levels of immunoreactive parathyroid hormone, calcitriol, calcium, phosphate, alkaline phosphatase, SCr, and hemoglobin, as well as proteinuria, blood pressure, and immunosuppressive treatment at several times: before PTx and at 7 days, 1 month, and then every 3 months post-PTx. After PTx we observed acute renal function deterioration until the third post-PTx month, when SCr levels returned to baseline values. We found no changes in blood pressure, although there was a trend toward a reduced dosage of antihypertensive drugs. We compared the patients who showed more significant increases (>30% from baseline) in SCr (group A, n = 7) with those who did not (group B, n = 15). Group A had higher SCr levels pre-PTx. We observed no other significant differences, either pre-PTx or post-PTx. In 2 patients in group A, SCr returned to baseline at the third month after PTx, but in the other 5 the renal function impairment persisted. Taking into account this risk and that severe hyperparathyroidism does not revert after transplantation, it would seem more appropriate in such cases to perform PTx while the patient is on the waiting list. The causes of this renal functional impairment are not clear, but the patients who showed worse deterioration also had a worse renal function pre-PTx.

A non-invasive method for measurement of gastric emptying in mice: effects of altering fat content and CCK A receptor blockade

The ability to make repetitive non-invasive measurements of gastric emptying of nutritive solids in awake, unstressed mice is highly desirable. The aim of the present study was to develop such a technique using nuclear scintigraphy and diets differing in triglyceride content. Awake mice were accustomed to light restraint and to feeding cooked, egg white (0.00 g fat g(-1)), whole egg (0.10 g fat g(-1)), or egg yolk (0.31 g fat g(-1)). Gastric emptying of each diet was measured by labelling the test meals with Technetium(99m) Mebrofenin and using a conventional gamma camera equipped with a high resolution, parallel hole collimator. Gastric emptying of cooked whole egg was also determined following administration of either vehicle or CCK A receptor antagonist, devazepide. The half-emptying time (t(1/2)) significantly increased with increasing triglyceride content from 14 +/- 5 min to 51 +/- 6 min and 82 +/- 4 min for egg white, whole egg and egg yolk, respectively. Administration of devazepide significantly decreased t(1/2) of whole egg to 28 +/- 2 min. These results demonstrate the sensitivity and predictability of this technique in mice and importantly, provide an opportunity to alter the macronutrient or caloric content of the meal to determine effects on gastric emptying.

Identification of genes regulated during osteoblastic differentiation by genome-wide expression analysis of mouse calvaria primary osteoblasts in vitro

Although several independent studies of gene expression patterns during osteoblast differentiation in cultures from calvaria and other in vitro models have been reported, only a small portion of the mRNAs expressed in osteoblasts have been characterized. We have previously analyzed the behavior of several known markers in osteoblasts, using Affymetrix GeneChip murine probe arrays (27,000 genes). In the present study we report larger groups of transcripts displaying significant expression modulation during the culture of osteoblasts isolated from mice calvaria. The expression profiles of 601 such regulated genes, classified in distinct functional families, are presented and analyzed here. Although some of these genes have previously been shown to play important roles in bone biology, the large majority of them have never been demonstrated to be regulated during osteoblast differentiation. Despite the fact that the precise involvement of these genes in osteoblast differentiation and function needs to be evaluated, the data presented herein will aid in the identification of genes that play a significant role in osteoblasts. This will provide a better understanding of the regulation of osteoblast differentiation and maturation.

Behavior of osteoblast, adipocyte, and myoblast markers in genome-wide expression analysis of mouse calvaria primary osteoblasts in vitro

Several genes, such as alkaline phosphatase, osteocalcin, and Cbfa1/Osf2, are known to be regulated during osteoblastic differentiation and are commonly used as "osteoblast markers" for in vitro or in vivo studies. The number of these genes is very limited, however, and it is of major interest to identify new genes that are activated or repressed during the process of osteoblast differentiation and bone formation as well as to extend the available information on gene families relevant to this particular differentiation pathway. To identify such genes, we have implemented a genome-wide analysis by determining changes in expression levels of 27,000 genes during in vitro differentiation of primary osteoblasts isolated from mouse calvaria. This study focuses on the description of the analytical and filtering process applied; on the transcriptional analysis of well-established "bone," "adipocyte," and "muscle" pathway markers; and on a description of the regulation profiles for genes recently described in the Skeletal Gene Database. We also demonstrate that new array technologies constitute reliable and powerful tools to monitor the transcription of genes involved in osteoblastic differentiation, allowing a more integrated vision of the biological pathways regulated during osteoblast commitment, differentiation, and function.

LDL receptor-related protein 5 (LRP5) affects bone accrual and eye development

In humans, low peak bone mass is a significant risk factor for osteoporosis. We report that LRP5, encoding the low-density lipoprotein receptor-related protein 5, affects bone mass accrual during growth. Mutations in LRP5 cause the autosomal recessive disorder osteoporosis-pseudoglioma syndrome (OPPG). We find that OPPG carriers have reduced bone mass when compared to age- and gender-matched controls. We demonstrate LRP5 expression by osteoblasts in situ and show that LRP5 can transduce Wnt signaling in vitro via the canonical pathway. We further show that a mutant-secreted form of LRP5 can reduce bone thickness in mouse calvarial explant cultures. These data indicate that Wnt-mediated signaling via LRP5 affects bone accrual during growth and is important for the establishment of peak bone mass.

[Medullary and intracranial metastases of myxopapillary ependymoma]

After a brief introduction about the clinical, histological and therapeutic characteristics of myxopapillar spinal ependymoma of cone medullar and filum terminale, three cases with medullar and intracranial seeding of myxopapillar spinal ependymoma are retrospectively reviewed. Surgical resection was total in the child and partial in the adult cases and the histological results were myxopapillar. The diagnosis was made by CT and MRI between 1-2 months before surgical treatment. No extra-neural tumour was found. The mechanisms and factors that influence the seeding of this type of tumour are discussed. The most important literature is reviewed and the cases discussed. The authors stress the importance of surgery on prognosis and the need of an MRI of the whole neural-axis, particularly in children, and subtotal exeresis in adults.

[Caudal regression syndrome. Lumbo-sacral agenesis]

Retrospective analysis of six cases of caudal regression syndrome, classified in accordance with vertebral envolvement. The degree of vertebral agenesis, morphology and topography of the conus medularis, neurologic implications (motor, sensitive and autonomous) and associated malformations, of particular importance in some situations of little significant vertebral agenesis are analyzed. Associations with eventual predisponent factors are sought.

Changes in iron status during pregnancy in peruvian women receiving prenatal iron and folic acid supplements with or without zinc

BACKGROUND

Iron deficiency anemia is the most prevalent nutrient deficiency during pregnancy, yet there are few data on the effect of prenatal iron supplementation in women in developing countries.

OBJECTIVE

Our objective was to describe the effect of iron supplementation on hematologic changes during pregnancy, and the effect on those changes of adding zinc to the supplements.

DESIGN

Pregnant women were enrolled in a randomized, double-masked study conducted at a hospital in a shantytown in Lima, Peru. Women were supplemented daily from 10-24 wk gestation to 4 wk postpartum with 60 mg Fe and 250 microg folic acid with or without 15 mg Zn. Hemoglobin and ferritin concentrations were measured in 645 and 613 women, respectively, at enrollment, at 28-30 and 37-38 wk gestation, and in the cord blood of 545 neonates.

RESULTS

No differences in iron status were detected by supplement type, but hematologic changes were related to initial hemoglobin status. Women with anemia (hemoglobin <110 g/L) showed steady increases in hemoglobin concentration throughout pregnancy whereas women with relatively higher initial hemoglobin concentrations had declining values during mid pregnancy, then rising values by 37-38 wk gestation. Women with an initial hemoglobin concentration >95 g/L showed increases in serum ferritin by the end of the pregnancy. Despite supplementation, women with poorer hematologic status; who were younger, single, and multiparous; and who consumed fewer supplements were more likely to have anemia at the end of pregnancy.

CONCLUSIONS

These hematologic changes are congruent with the effects of iron supplementation reported in placebo-controlled trials and the addition of zinc did not significantly affect them.

Efficacy and acceptability of two iron supplementation schedules in adolescent school girls in Lima, Peru

To assess the efficacy and acceptability of a daily and intermittent iron supplementation, a double-blind, placebo-controlled trial was conducted in a public school located in periurban Lima, Peru. Adolescent girls (n = 312), 12-18 y old, were randomly assigned to one of the following three groups: 1) 60 mg iron as ferrous sulfate daily from Monday to Friday; 2) 60 mg iron as ferrous sulfate 2 d/wk and 3 d placebo (intermittent); 3) placebo, from Monday to Friday. Field workers gave the girls supplements during school hours for 17 wk; 296 girls completed the trial. Girls took 94% of the expected dose of 85 pills. Few side effects were reported. Postintervention, hemoglobin (Hb), serum ferritin (SF) and free erythrocyte protoporphyrin (FEP) were improved significantly in the iron-supplemented groups compared with placebo (P<0.05). Daily supplements led to higher Hb increases than intermittent supplements (P<0.05), but SF and FEP were similar between the two groups. Thus, both iron supplementation schedules were efficacious in preventing iron deficiency in adolescent girls through the school system, and the daily schedule was better than the intermittent schedule at increasing Hb values and reducing anemia.

Cardiac troponin T as a marker for myocardial ischemia in patients seen at the emergency department for acute chest pain

BACKGROUND

Identification of patients with acute chest pain at high risk for cardiovascular complications is a common and difficult challenge for clinicians and must be based initially on data from the history, physical examination, electrocardiogram, and chest radiograph. Some data suggest that elevations in cardiac troponin T (cTnT) may be useful for detection of less severe degrees of myocardial injury that may occur in some patients with unstable angina. Therefore we designed a prospective follow-up study to assess the diagnostic performance and prognostic value of cTnT in a population of patients presenting to the emergency department with acute chest pain.

METHODS

The patient population included all 1477 admitted patients aged 30 years or more who presented to the emergency department of an urban teaching hospital from October 1992, through February 1994, with a chief symptom of acute chest pain not explained by trauma or chest radiograph abnormalities. The 1303 patients (88%) who had 2 or more measurements of cTnT during the first 24 hours after presentation comprised the final study population. Sensitivity, specificity, positive predictive value, negative predictive value, and receiver operator characteristics curve (ROC) were determined for cTnT and creatine kinase-MB (CK-MB) (measured using activity and mass assays) data from the first 24 hours after admission for the outcomes of acute myocardial infarction (AMI) and major cardiac events during the first 72 hours of hospitalization.

RESULTS

The sensitivity and specificity of cTnT (threshold of 0.1 ng/mL) for detecting AMI during the first 24 hours after presentation were 99% and 86%, respectively. The CK-MB activity and mass assays had diagnostic performance for detecting AMI similar to cTnT. Among patients who did not meet study criteria for AMI, cTnT was elevated during the first 24 hours in 31% of patients who had major complications, compared with a 17% rate for the CK-MB activity assay and a 3% rate for the CK-MB mass assay. In these patients, the cTnT assay had superior diagnostic performance compared with the CK-MB mass assay as a marker for cardiac complications as assessed with ROC analysis (P <.0004).

CONCLUSIONS

In a heterogeneous population of patients seen in the emergency department with acute chest pain, cTnT was similar to CK-MB (activity and mass assays) for detection of AMI and superior to the CK-MB mass assay as a marker for major cardiac events early in the hospital course among those who were ruled out for an AMI. Further study is required to determine how this assay can be used to provide more appropriate, cost-effective care.