Opposing effects of DHEA replacement in elderly subjects on declarative memory and attention after exposure to a laboratory stressor

Aging is accompanied by a continuous decline of the adrenal steroid hormone DHEA and its ester DHEAS. Results from studies in rodents have demonstrated that DHEA(S) administration can enhance memory in several test paradigms. However studies from this laboratory did not find positive effects of DHEA treatment on cognitive performance in young and elderly humans. With respect to a possible mechanism of DHEA activity, effects on several neurotransmitter receptors as well as a possible antiglucocorticoid action are discussed. For high levels of glucocorticoids, a disruptive effect on hippocampal mediated memory is documented in rodents and humans. Therefore it was speculated that, if an antiglucocorticoid action of DHEA would underlie the observed beneficial effects of DHEA on memory, these effects might only be detectable if subjects are stressed (and therefore have high cortisol levels). To test this hypothesis 75 elderly women and men participated in a placebo controlled experiment. Subjects took DHEA (50 mg/day) or placebo for 2 weeks (double blind). Thereafter they participated in a standardized psychosocial laboratory stressor (Trier Social Stress Test; TSST). Before and after stress exposure subjects completed two declarative memory tests (visual-verbal and spatial) as well as one attention test. In addition recall of visual material learned before stress was assessed after stress. Baseline DHEAS levels were significantly lower compared with young adults. DHEA replacement increased DHEAS levels into ranges found in young subjects. DHEA-substituted subjects showed a trend towards a larger cortisol stress response. In the visual memory test subjects under DHEA recalled less items after stress which they had learned before stress. In the attention test however subjects under DHEA performed better than subjects from the placebo group after stress. No interaction between stress and DHEA was found for the spatial memory task. The effects of DHEA substitution on memory and attention after stress exposure seem to be heterogenous. While recall of previously learned material seems to be impaired, attention is enhanced. These results do not support the idea of a direct antiglucocorticoid or anti-stress effect of DHEA on hippocampal mediated memory functions.     

Heterogeneity of variances for carcass traits by percentage Brahman inheritance

Heterogeneity of carcass trait variances due to level of Brahman inheritance was investigated using records from straightbred and crossbred steers produced from 1970 to 1988 (n = 1,530). Angus, Brahman, Charolais, and Hereford sires were mated to straightbred and crossbred cows to produce straightbred, F1, back-cross, three-breed cross, and two-, three-, and four-breed rotational crossbred steers in four non-overlapping generations. At weaning (mean age = 220 d), steers were randomly assigned within breed group directly to the feedlot for 200 d, or to a backgrounding and stocker phase before feeding. Stocker steers were fed from 70 to 100 d in generations 1 and 2 and from 60 to 120 d in generations 3 and 4. Carcass traits included hot carcass weight, subcutaneous fat thickness and longissimus muscle area at the 12-13th rib interface, carcass weight-adjusted longissimus muscle area, USDA yield grade, estimated total lean yield, marbling score, and Warner-Bratzler shear force. Steers were classified as either high Brahman (50 to 100% Brahman), moderate Brahman (25 to 49% Brahman), or low Brahman (0 to 24% Brahman) inheritance. Two types of animal models were fit with regard to level of Brahman inheritance. One model assumed similar variances between pairs of Brahman inheritance groups, and the second model assumed different variances between pairs of Brahman inheritance groups. Fixed sources of variation in both models included direct and maternal additive and nonadditive breed effects, year of birth, and slaughter age. Variances were estimated using derivative free REML procedures. Likelihood ratio tests were used to compare models. The model accounting for heterogeneous variances had a greater likelihood (P < .001) than the model assuming homogeneous variances for hot carcass weight, longissimus muscle area, weight-adjusted longissimus muscle area, total lean yield, and Warner-Bratzler shear force, indicating improved fit with percentage Brahman inheritance considered as a source of heterogeneity of variance. Genetic covariances estimated from the model accounting for heterogeneous variances resulted in genetic correlations of or near unity. These results suggest that different genetic values be considered for genetic evaluation of carcass yield and shear force traits from steers with different degrees of Brahman inheritance.     

Expression and purification of HIV-I p15NC protein in Escherichia coli

M2 is a minor component of the influenza A virus envelope. The cytoplasmic tail of the M2 protein is posttranslationally modified in the infected cell by palmitylation and phosphorylation. The primary site for phosphorylation of the M2 cytoplasmic tail is serine 64, which is highly conserved yet not required for the activity of the M2 ion channel. Using an exogenous incorporation assay, we have shown that incorporation of M2 into virus particles is type-specific and does not require phosphorylation of the cytoplasmic tail. In addition, phosphorylation of the cytoplasmic tail is not required for the directional transport of M2 in polarized MDCK cells. Using a reverse genetics and reassortment procedure, we generated a virus (Ra) specifically mutated in segment 7 such that the M2 cytoplasmic tail could no longer be phosphorylated. The virus was found to grow as well as wild-type virus in tissue culture and in eggs, was stable on passage in these systems, and possessed no second-site mutations in the engineered RNA segment. In vivo Ra replicated in Balb/c mice at least as well as the parent strain A/WSN/33. These studies indicate that phosphorylation of the M2 cytoplasmic tail is not required for in vitro or in vivo replication of influenza A virus.     

Inhibition of nitric oxide synthase for treatment of experimental autoimmune encephalomyelitis

Aminoguanidine (AG), a selective inhibitor of inducible nitric oxide synthase, prevented the clinical development of experimental autoimmune encephalomyelitis (EAE) with a reduction in inflammation and demyelination. Administration of AG reduced the expression of nitrosotyrosine in inflammatory lesions in the central nervous system. Cytokine expression, determined by semiquantitative PCR, revealed increased expression of IFN-gamma, IL-10, and TGF-beta, which was associated with protection from EAE, and reduced TNF-alpha, associated with the development of EAE. Furthermore, AG blocked the secretion of nitric oxide, TNF-alpha, and PGE2 in astrocyte cultures. AG did not influence the proliferation response of T cells to a pathogenic epitope of myelin basic protein. Down-regulation of nitric oxide by AG has widespread consequences for cytokine production in central nervous system inflammation and prevents EAE.     

Detection of trisomy 3 in primary gastric B-cell lymphoma by using chromosome in situ hybridization on paraffin sections

Recently, new backscatter factors for low-energy x rays derived from Monte Carlo calculations have been recommended in the UK code of practice for kilovoltage dosimetry published by (IPEMB). As these data, presented as a function of half-value layer, do not take account of the variation of the x-ray spectra for a given HVL, we have undertaken an experimental study in order to determine BSG for the beam qualities provided by a Darpac 2000 therapy unit. A RTL detector such as Li2B4O7:Cu and parallel-plate ion chambers specially designed for low-energy x-ray dosimetry have been used. The results obtained show very good agreement between the TLD and the Monte Carlo calculations, confirming values obtained by other authors with lithium borate TLD. On the contrary, the results obtained with plane-parallel ion chambers show discrepancies up to 9% that are discussed.     

Superiority of tandem autologous transplantation over standard therapy for previously untreated multiple myeloma

Virtually no progress has been made during more than 2 decades of clinical trials for multiple myeloma (MM) involving standard therapy (ST). Recent studies suggest that dose intensification requiring hematopoietic stem cell support results in higher complete response (CR) rates and extended disease control. "Total Therapy" (TT) consisting of noncross-resistant induction regimens, followed by a double autotransplant (AT) procedure, was administered to 123 untreated patients with symptomatic MM. Upon hematologic recovery, interferon (IFN) maintenance (3 million units [MU]/m2 subcutaneously thrice weekly) was given until disease recurrence/progression. Results were compared with the outcome of untreated patients receiving ST according to Southwest Oncology Group (SWOG) trials. One hundred sixteen pair mates were selected from both TT and among 1,123 patients to match for the major prognostic features. TT induced CR in 40% of all 123 patients (intent-to-treat). By 12 months, 7% had died, including 4% from treatment-related complications. With a median follow-up of 31 months, median durations of event-free survival (EFS) and overall survival (OS) are 49 and 62+ months, respectively. Abnormalities of chromosomes 11q and 13 were associated with inferior outcome, whereas CR within 6 months after induction was a favorable prognostic feature for both EFS and OS. In comparison to ST, TT induced higher PR rates (85% v 52%, P < .0001) (CR rates not available on SWOG trials) and extended EFS (49 v 22 months, P = .0001) and OS (62+ v 48 months, P = .01). Compared to ST, dose intensification with double AT markedly augments tumor cytoreduction, effecting not only higher CR rates but also significantly extending EFS and OS in previously untreated patients with MM.     

Sequence-related behaviour of transmembrane domains from class I receptor tyrosine kinases

The purpose of this study was to investigate the effects of 316L stainless steel (SS) corrosion products on the in vitro biomineralization process, because tissue necrosis, bone loss, impaired bone mineralization, and loosening of orthopedic implants are associated with ions and debris resulting from biodegradation. Rat bone marrow cells were cultured in experimental conditions that favored the proliferation and differentiation of osteoblastic cells and were exposed to SS corrosion products obtained by electrochemical means for periods ranging from 1 to 21 days. Quantification of total and ionized Ca and P, as well as Fe, Cr, and Ni, ions in the culture media of control and metal added cultures during the incubation period was performed to study the influence of corrosion products on the Ca and P consumption that occurs during the mineralization process. Control cultures and metal effects on cultures were evaluated concerning DNA content, enzymatic reduction of 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT), and alkaline phosphatase (ALP) activity. Histochemical detection of ALP, Ca, and phosphate deposition, and examination of the cultures by scanning and transmission electron microscopy (SEM and TEM) were also performed. The presence of SS corrosion products resulted in impairment of the normal behavior of rat bone marrow cultures. Levels of Cr and Ni in the medium of cultures exposed to 316L SS corrosion products decreased throughout the incubation period, suggesting a regular deposition of these species; these results were supported by TEM observation of the cultures. Cultures exposed to the corrosion products presented lower DNA content, MTT reduction, and ALP activity and failed to form mineralized areas. These cultures showed negative staining on histochemical reactions for the identification of calcium and phosphate deposition and SEM and TEM examination did not show mineral globular structures or mineralization foci, respectively, which is characteristic of cultures grown in control conditions. These results suggest that metal ions associated with 316L SS are toxic to osteogenic cells, affecting their proliferation and differentiation.     

Reconstruction of total maxillectomy defects with preservation of the orbital contents

Reconstruction after total maxillectomy with preservation of the orbital contents is technically more challenging than when the maxillectomy is combined with orbital exenteration. Reconstruction of such defects should (1) provide support to the orbital contents, (2) obliterate any communication between the orbit and nasopharynx, (3) reconstruct the palatal surface, and (4) achieve facial symmetry and a good aesthetic result. We report our experience in performing reconstructive surgery on 14 patients who had a total maxillectomy and preservation of the orbital contents using nonvascularized bone grafts for reconstruction of the orbital floor and maxilla, in conjunction with a soft-tissue free flap or pedicled muscle flap. The orbital floor was reconstructed using split ribs in six cases (42.9 percent), split calvaria in six cases (42.9 percent), and iliac crest graft in two cases (14.3 percent). A myocutaneous rectus abdominis free flap was used for soft-tissue reconstruction and resurfacing of the palatal mucosa in twelve patients (85.7 percent), and a temporalis muscle transposition was used in two elderly patients (14.3 percent). One patient died 2 days after surgery. Mean follow-up and aesthetic and functional results were assessed in the remaining 13 patients a minimum of 6 months postoperatively. In 9 of these 13 patients (69.2 percent), postoperative radiotherapy was administered. No reexplorations or free flap failures were observed. One rectus flap developed partial necrosis of the skin island intraorally without affecting the final result. All patients had adequate functional vision. One patient had a mild vertical dystopia; there were no cases of enophthalmos. Ectropion was the most common undesirable result and was present in 10 of 13 cases (76.9 percent). It was graded as mild in four cases (40.0 percent), moderate in four cases (40.0 percent), and severe in the remaining two cases (20.0 percent). Speech was considered normal in six cases (46.2 percent), near normal in six cases (46.2 percent), and intelligible in one case (7.7 percent). Chewing function was considered good (soft to unrestricted diet) in all cases except for one patient who was only able to eat a pureed diet. Aesthetic results after immediate reconstruction were considered good in nine cases (69.2 percent) and fair in four cases (30.8 percent). Primary reconstruction of total maxillectomy defects with orbital content preservation remains a complex problem without a perfect solution. The combination of nonvascularized bone grafts for orbital/maxillary reconstruction with a soft-tissue free flap is a safe, reliable, and effective method of maximizing postoperative functional and aesthetic results.