Effects of retention interval length on young and elderly adults' memory for spatial information

Adult age differences in spatial memory following retention intervals of various lengths were examined in 47 young and 56 elderly subjects who recalled spatial information following either a 3-, 15-, or 30-min retention interval. The elderly adults were significantly less accurate than the young adults following the 30-min retention interval only; there was no statistically significant effect of age at the 3-min and 15-min retention intervals. It is concluded that younger adults experience greater temporal stability of spatial memory than do older adults, and the relevance of the present findings for Craik's environmental support hypothesis is discussed.

Assessing capacity to participate in discussions of advance directives in nursing homes: findings from a study of the Patient Self Determination Act

OBJECTIVE

To better understand the implementation of the Patient Self-Determination Act (PSDA) in long-term care, with a focus on the informing process as it affects advance directives.

DESIGN

Retrospective cohort study of nursing home admissions, using medical record reviews, and a companion qualitative survey using key informant interviews.

SETTING

Eleven nursing homes in Connecticut.

PARTICIPANTS

A total of 600 residents randomly selected from six randomly chosen nursing homes and 19 key informants selected from five purposely sampled nursing homes in Connecticut.

MEASURES

Institutional compliance with the PSDA requirement to provide written information about advance directives at admission and aspects of the informing process, including to whom the information is given.

RESULTS

Compliance with the PSDA requirement to provide information at admission is high (90.7 of admissions in the post-PSDA cohort received information within 1 week of admission). However, in nearly 70% of admissions in which information was provided, someone other than the residents received the information. Staff often cited the resident's cognitive impairment as a reason for excluding residents from this informing process. However, even among those residents judged to be alert and oriented at admission, someone other than the resident received the information 47.7% of the time.

CONCLUSIONS

Substantial numbers of residents may be inappropriately excluded from participating in discussions because of difficulties in determining decisional capacity to discuss future treatment wishes. The research highlights the difficulties of enhancing resident participation and autonomy in long-term care through procedural regulations such as the PSDA. More reliable methods of determining resident decisional capacity are needed to integrate the full intent of the PSDA into clinical practice in long-term care.

Effects of antigen presentation on superantigen-induced apoptosis mediated by Fas/Fas ligand interactions in human T cells

Stimulation of T cells with bacterial superantigens has several distinct functional outcomes including proliferation, anergy and apoptosis. At present however, the mechanisms that dictate whether activation, anergy, or apoptosis predominate are unclear. In this study we have investigated the effects of superantigen presentation to mature superantigen-reactive human T-cell lines. Despite expressing major histocompatibility complex (MHC) class II molecules, these lines failed to proliferate in response to superantigen in the absence of antigen-presenting cells (APC) but proliferated when minimal APC were added. In the absence of APC a significant proportion of the T cells underwent apoptosis. This response was rapid, antigen dependent and largely abolished by the addition of cyclosporin A. Interestingly the response was not blocked by the addition of a number of antibodies to cell surface molecules including MHC class II and intracellular adhesion molecule-1. Using both a bioassay and messenger RNA analysis we were able to demonstrate that stimulation of these T cells with superantigen resulted in the induction of Fas-ligand expression on the T cells and furthermore, the ability of these cells to induce apoptosis was inhibited by the addition of blocking Fas antibodies as well as a Fas-Fc fusion protein. These data demonstrate that stimulation of T cells with staphylococcal enterotoxin B induces expression of Fas-ligand resulting in T-cell apoptosis; however, the final outcome of proliferation or apoptosis is determined by the presence of APC.

Development of drug targeting based on recombinant expression of the chicken avidin gene

The chemistry required for covalent biotinylation of drugs, radiopharmaceuticals and other ligands is highly developed, and a large number of biotinylated reagents can be readily synthesized. In order to investigate whether expression of avidin cDNA in mammalian cells might be useful as part of a drug targeting strategy, we transiently expressed the avidin gene in two human tumor cell lines (the cervical carcinoma cell line, HeLa, and the liver derived line, Hep G2). Avidin protein as detected by either immunohistochemistry or binding of streptavidin-biotin complexes was present and functional following transient expression. This result indicated that the mechanisms underlying avidin oligomerization which are necessary for proper protein folding are present within mammalian carcinoma cell lines. Next, we generated a producer cell line (derived from psi2) capable of releasing a recombinant retrovirus encoding chicken avidin, and a tumorigenic murine breast cancer cell line (16/C) with stable avidin expression. We show that these cell lines are suitable for conferring functional expression of avidin in vitro. These experiments establish a means by which avidin gene expression can be explored as a mechanism for targeted gene delivery of biotin-derivitized drugs in vitro, and have important implications for utilization of this strategy in vivo.

Regulation of renal tubular sodium transport by angiotensin II and atrial natriuretic factor

1. The effects of angiotensin II (AngII) on water and electrolyte transport are biphasic and dose-dependent, such that low concentrations (10(-12) to 10(-9) mol/L) stimulate reabsorption and high concentrations (10(-7) to 10(-6) mol/L) inhibit reabsorption. Similar dose-response relationships have been obtained for luminal and peritubular addition of AngII. 2. The cellular responses to AngII are mediated via AT1 receptors coupled via G-regulatory proteins to several possible signal transduction pathways. These include the inhibition of adenylyl cyclase, activation of phospholipases A2, C or D and Ca2+ release in response to inositol-1,4,5,-triphosphate or following Ca2+ channel opening induced by the arachidonic acid metabolite 5,6,-epoxy-eicosatrienoic acid. In the brush border membrane, transduction of the AngII signal involves phospholipase A2, but does not require second messengers. 3. Angiotensin II affects transepithelial sodium transport by modulation of Na+/H+ exchange at the luminal membrane and Na+/HCO3 cotransport, Na+/K(+)-ATPase activity and K+ conductance at the basolateral membrane. 4. Atrial natriuretic factor (ANF) does not appear to affect proximal tubular sodium transport directly, but acts via specific receptors on the basolateral and brush border membranes to raise intracellular cGMP levels and inhibit AngII-stimulated transport. 5. It is concluded that there is a receptor-mediated action of ANF on proximal tubule reabsorption acting via elevation of cGMP to inhibit AngII-stimulated sodium transport. This effect is exerted by peptides delivered at both luminal and peritubular sides of the epithelium and provides a basis for the modulation by ANF of proximal glomerulotubular balance. The evidence reviewed supports the concept that in the proximal tubule, AngII and ANF act antagonistically in their roles as regulators of extracellular fluid volume.

Extensive areas of aneuploidy are present in the respiratory epithelium of lung cancer patients

According to the field cancerisation theory the entire upper aerodigestive tract has been mutagenised, thereby placing the affected individual at risk for the development of one or more cancers. To investigate this concept we studied the respiratory epithelium in lungs bearing cancer, including bronchi, bronchioles and alveoli. After identifying preneoplastic and preinvasive lesions by light microscopy, we determined the DNA content of their nuclei in Feulgen-stained sections using a high-performance digitised image analyser. Archival material from 35 resected cases of non-small-cell lung cancer (NSCLC) was selected, including 16 central tumours (mainly squamous cell carcinomas) and 19 peripheral tumours (mainly adenocarcinomas) and five resected cases of metastatic tumour from extrathoracic primary sites. Of the NSCLCs, 31/35 (89%) were aneuploid, as were 60% of the metastases from extrathoracic sites. Multiple, focal areas of preneoplasia or preinvasive carcinoma were present in the selected cases. The lesions ranged in severity from hyperplasia through metaplasia and dysplasia to carcinoma in situ. Aneuploid preinvasive lesions were not noted in association with the four diploid tumours but were present only when the accompanying NSCLC was aneuploid. With both central and peripheral tumours, aneuploid preneoplastic lesions were more frequent in the peripheral parts of the lung (bronchioles or alveoli) than in the central bronchi. Both the degree and incidence of aneuploidy increased with progressive severity of morphological change. Aneuploidy was not found in preinvasive lesions accompanying the five metastatic cases. Our findings provide strong support for the concept of field cancerisation.

The practice of primary health care: a case study

This paper focuses on the practice of Primary Health Care in Soweto. It does so through an investigation into the work of a group of Primary Health Care Nurses (PHCNs) who are based in Community Health Care Centres in Soweto. This paper highlights the conflictual and contradictory conditions under which the Primary Health Care Nurses are working and further documents gaps and weaknesses in the practice and training of PHCNs. The paper argues that a central weakness is the apparent lack of social awareness and gender sensitivity amongst the group of Primary Health Care Nurses studied.

Flow cytometric staining of pancreatic endocrine cells

Few distinct surface markers have been identified for endocrine cells, but antibodies directed against hormonal epitopes are widely available. In this study, human fetal pancreatic beta cells were identified on the flow cytometer by intracellular staining for insulin. A paraformaldehyde based permeabilization scheme was used which preserves surface staining and helps maintain cell integrity while allowing antibodies access to compartments within the cell interior. Cells were first stained for surface antigens, fixed in paraformaldehyde, and then permeabilized in phosphate buffered saline containing 0.2 percent Tween. Intracellular staining was accomplished using a fluorescein conjugated anti-insulin monoclonal antibody. In this manner, major histocompatibility complex Class II antigen expression was documented on beta cells exposed to interferon gamma. This study demonstrates the feasibility of using hormonal content to identify endocrine cells by flow cytometry while simultaneously staining for surface antigens.

Treatment of mandibular angle fractures using two noncompression miniplates

PURPOSE

To evaluate treatment with two 2.0-mm noncompression miniplates for patients with angle fractures.

PATIENTS AND METHODS

Sixty-seven consecutive patients with 69 fractures of the mandibular angle were treated by open reduction and internal fixation using two noncompression miniplates and 2.0-mm self-threading screws placed through a transoral incision with transbuccal trochar instrumentation. No patient was placed into postsurgical maxillomandibular fixation or elastics.

RESULTS

Overall, 19 fractures (28%) experienced complications requiring secondary surgical intervention. Most of the complications were postoperative infections requiring surgical drainage (n = 17) and subsequent hardware removal (n = 16). Of the 17 infected fractures, 11 were healed at the time of hardware removal and required no further treatment. Five were still mobile and required a period of maxillomandibular fixation for healing. One of the fractures did not heal and required bone grafting.

CONCLUSION

The use of two noncompression miniplates was found to be relatively easy, but resulted in an unacceptable rate of infection in our patient population when used for treatment of fractures of the mandibular angle.

Human fetal islet response to interferon gamma

Investigation was made of the ability of human fetal islets to express major histocompatibility complex class I and class II gene products after in vitro exposure to 1,000 U/ml Interferon Gamma (IFN) for 48 hours as well as the effect of such exposure on insulin secretion and autologous mixed islet lymphocyte response. Flow cytometry analysis revealed that the mean fluorescence activity of both HLA-ABC (class I) and HLA-DR (class II) was significantly (p < 0.01) increased vs the control after IFN incubation. (class I: Control = 125 +/- 35 SD, IFN = 995 +/- 418 S.D.; class II: Control = 70 +/- 30 SD, IFN = 300 +/- 74 S.D.). Cells containing surface expression of DR and intracellular insulin by flow cytometry following depletion of phagocytic cells were also quantified and increased from 0 to 0.67 percent following exposure to IFN. Autologous splenocytes responded to cells previously incubated with IFN with a three fold increase in 3H-thymidine uptake. Interferon gamma exposed, DR positive insulin containing cells contained one third the insulin of DR negative insulin containing cells (2.1 +/- 1.5 vs 6.6 +/- 3.4 microU/cell) but were nevertheless capable of stimulated insulin secretion. Thus, pharmacologic events leading to increased fetal pancreatic interferon concentrations initiate both immune and nonimmune processes that may predispose susceptible individuals to diabetes.

Unlocking the information vault

With a multitude of departmental information systems, executives find it difficult to make well-informed decisions affecting cost or to change physician behavior. A well-conceived EIS is alleviating such difficulties at many organizations.

Unlocking the information vault

With a multitude of departmental information systems, executives find it difficult to make well-informed decisions affecting cost or to change physician behavior. A well-conceived EIS is alleviating such difficulties at many organizations.

The contributions of renin and vasopressin to the adaptation of the Australian spinifex hopping mouse (Notomys alexis) to free water deprivation

Xeric-adaptation was studied during 28 days of total water deprivation (TWD) in Notomys alexis. Beyond 7 days, the initial reductions in body weight and increases in haematocrit, plasma renin and juxtaglomerular (JG) cell morphological activity returned to normal. Mus musculus showed similar changes at 7 days but could not be maintained thereafter. TWD decreased the blood pressure of Notomys but endogenous angiotensin and vasopressin did not support pressure to a greater extent than controls, as revealed by selective antagonists. The normal morphology of the JG apparatus in Notomys was similar to other rodents. Fluid volume and blood pressure maintenance during TWD in Notomys do not depend upon enhanced activities of the renin-angiotensin and antidiuretic hormonal systems.

Cell cycle activity and expression of prohibitin mRNA

Prohibitin, a novel intracellular antiproliferative protein, blocks entry into the S phase of the cell division cycle when its mRNA is microinjected into normal fibroblasts or HeLa cells. To learn more about the interaction between prohibitin and the cell cycle, we studied the effect of microinjecting prohibitin mRNA at different points during the transition from G0 to S phase and analyzed prohibitin mRNA and protein levels in different parts of the cell cycle. The antiproliferative activity of microinjected prohibitin mRNA is high in G0/G1 and falls as cells approach S phase. Prohibitin mRNA and protein levels are high in G1, fall with S phase, rise again in G2, and fall in M. Together, these findings suggest that endogenous prohibitin contributes to the control of the G1 to S transition in cycling cells in a complex manner, which involves both a transcriptional and posttranslational mechanism.