Ruminative coping with depressed mood following loss

In a longitudinal study of 253 bereaved adults, people with poorer social support, more concurrent stressors, and higher levels of postloss depression reported more rumination than people with better social support, fewer stressors, and lower initial depression levels. Women reported more rumination than men. People with a ruminative style at 1 month were more likely to have a pessimistic outlook at 1 month, which was associated with higher depression levels at 6 months. People with a more ruminative style were more depressed at 6 months, even after controlling for initial depression levels, social support, concurrent stressors, gender, and pessimism. Additional stressors and high depression scores at 1 month were also associated with higher levels of depression at 6 months.

Effects of cyclothiazide on synaptic responses in slices of adult and neonatal rat hippocampus

The effects of cyclothiazide, a drug that blocks AMPA receptor desensitization, on synaptic responses were studied in field CA1 of hippocampal slices from adult and neonatal rats. Cyclothiazide (100 microM) reliably increased AMPA receptor-mediated field EPSP decay times in adult slices but only after prolonged (60-120 min) applications. In neonatal slices, 30 min applications of cyclothiazide were sufficient to produce large and long-lasting increases in response decay times. Since the effects of cyclothiazide on AMPA receptor binding properties were similar in adult and neonatal forebrain membranes, the data indicate that the slow action of the drug in adult slices is probably due to diffusion barriers. The prolongation of EPSP decay by cyclothiazide suggests that AMPA receptor-mediated synaptic responses in hippocampus are terminated by receptor desensitization.

Waveform analysis suggests that LTP alters the kinetics of synaptic receptor channels

The waveform of an isolated excitatory monosynaptic response reflects the kinetics of transmitter release, the kinetics of synaptic receptor channels and the filtering properties of neurons. Results reported here indicate that long-term potentiation (LTP) causes correlated decreases in the rise time and decay time constant of synaptic potentials recorded in hippocampal slices in which inhibitory currents and post-synaptic spiking were suppressed. Statistical comparisons of waveforms revealed that the distortions introduced by LTP could be corrected by stretching the time-scale of potentiated responses according to the percent change in the decay time constant. The LTP associated decrease in the decay time constant also obtained in slices from immature hippocampus which contain spines and dendrites greatly simplified from those of the adult. Hence, filtering properties of spines are not likely involved in the effect. Paired-pulse facilitation (PPF), a transient increase in transmitter release, did not reproduce the waveform effects of LTP but did cause a slight leftward shift of the response. These results suggest that LTP modifies the kinetics of receptor channels, and that PPF accelerates release.

Case report: nuclear magnetic resonance imaging in a patient with a pacemaker

The presence of a pacemaker has been considered a contraindication for magnetic resonance imaging (MRI) examination. The authors describe a patient with a pacemaker who underwent MRI of the head without sequelae. Spine-echo MRI was preformed with 1.5 Tesla imager using head coil only. Prior to imaging, the pacemaker was programmed to the OOO mode. In carefully selected pacing-independent patients, with a pacemaker in a bipolar configuration, MRI of the head appears to be safe provided the pacemaker is programmed to OOO and enough scar tissue has developed to prevent pacemaker or lead movement.

cDNA equalization for reverse transcription-polymerase chain reaction quantitation

Reverse transcription coupled with the polymerase chain reaction has been increasingly utilized to study gene expression. However, most previously published quantitative techniques are limited by accurate initial RNA quantitation and do not account well for the relative efficiency of reverse transcription. We have developed a technique of labeling and quantitating the random-primed cDNA product of a reverse transcription reaction. Using the polymerase chain reaction in conjunction with template dilutions or with an internal competitive template, we show that by normalizing the cDNA input into the polymerase chain reaction, we get accurate quantitation of gene expression. We call this procedure cDNA equalization of reverse transcriptase-polymerase chain reaction. This method is ideal for small clinical samples where accurate quantitation of input RNA is difficult.

Reversal of LTP by theta frequency stimulation

Reversal of long-term potentiation (LTP) by physiological stimulation was tested in the CA1 field of hippocampal slices. In control medium, a one minute episode of 5 Hz (theta frequency) stimulation beginning 1-3 min after LTP had no effect on the degree of potentiation measured 30 min later. However, in the presence of norepinephrine (200 microM), 5 Hz stimulation reduced LTP by about 30%. Theta frequency stimulation was only effective when administered within 10 min of LTP induction and had no lasting effects on non-potentiated synapses. Stimulation at 1 Hz did not reverse LTP and stimulation at 10 Hz was no more effective than 5 Hz stimulation. LTP could be nearly completely reversed by theta frequency stimulation when potentiation was induced by milder and more naturalistic stimulation patterns. Under these conditions, LTP reversal was blocked by an antagonist of adenosine A1 receptors. These results suggest that the hippocampal theta rhythm promotes both the induction of LTP and its subsequent reversal with the latter process involving activation of adenosine receptors. Reversal of LTP may function to refine or sharpen recently encoded representations.

Improving elders' continence state

A 6-month study was conducted to assess the effects that noninvasive self-managed interventions on 12 remediable risk factors had on elder's urinary continence status. Each remediable risk factor was linked with a criterion meeting normal and if not normal, one or more interventions. Continence history assessments were conducted monthly on 31 elders (M age = 67.65 years). After the first assessment, elders were identified as continent, incontinent or at risk for loss of continence. At the end of the 6 months, 9 of the 11 incontinent elders moved to the at-risk group and the other 2 remained incontinent, and 12 of the 20 at-risk elders became continent. Both the elders who were initially at risk and those who were incontinent had a statistically significant reduction in the number of remediable risk factors reported at the end of the study period. The assessments and interventions are useful.

Theta burst stimulation is optimal for induction of LTP at both apical and basal dendritic synapses on hippocampal CA1 neurons

The efficacy of stimulation patterns consisting of brief high frequency bursts repeated at various intervals to induce long-term potentiation (LTP) at synapses on apical and basal dendrites of CA1 hippocampal neurons was tested in vitro. Both apical and basal dendritic synapses exhibited maximal LTP after bursts repeated at 5-10 Hz, i.e. close to the frequency of the endogenous hippocampal theta rhythm. As at apical dendritic synapses, LTP at basal dendritic synapses was blocked by an antagonist of NMDA receptors. Basal dendritic LTP was significantly greater in magnitude than apical dendritic LTP, although the reason for this is unknown.

The healing web. A transformative model for nursing. Part II

The author and contributors continue the article that began in the February issue of Nursing & Health Care on the Healing Web project, "a collaborative effort of creative spinning and weaving." The purpose of the creative web management is to facilitate the healing of wounds within nursing and between nursing and medicine.

Handwashing practices and resistance and density of bacterial hand flora on two pediatric units in Lima, Peru

The handwashing practices and bacterial hand flora of 62 pediatric staff members of a teaching hospital in Lima, Peru, were studied. Handwashing followed patient contact 29.3% of the time (204/697 contacts). Mean duration was 14.5 seconds, and significant differences in practices were found by unit (rehydration or neonatal intensive care), type of staff member (nurses or physicians), and type and duration of patient contact. Mean count of colony-forming units was log10 5.87 +/- 0.41, with significant differences in density of flora found between patient care and kitchen staffs. There was no significant effect of handwashing on counts of colony-forming units. Significant differences were also found by unit and by staff position with regard to species isolated and antimicrobial resistance of isolates. A more efficacious and cost-effective form of hand hygiene and a more prudent use of antimicrobial agents are indicated.

Evidence that changes in spine neck resistance are not responsible for expression of LTP

From modeling studies it is known that changes in spine neck resistance can influence the shape of the non-linear curve relating synaptic current to synaptic conductance if the resistance of the neck approaches the synaptic input resistance. Such work also indicates that the effects of resistance will be much more pronounced for fast rather than slow synaptic currents. Accordingly, a reduction in neck resistance could produce an increase in the rapid responses generated by the quisqualate/AMPA class of glutamate receptors while only minimally affecting the slower NMDA receptor-mediated responses and thus account for the pattern of changes known to be associated with long-term potentiation (LTP). This hypothesis predicts that large reductions in synaptic conductance should have disproportionate effects on potentiated versus control responses. This was tested by using field potential recordings of synaptic currents in CA1 pyramidal cells in hippocampal slices in response to stimulation of Schaffer/commissural inputs that either received LTP-inducing stimulation or did not. Two manipulations were used to systematically reduce synaptic conductances: reductions of extracellular Ca++ and partial blockade of postsynaptic receptors. Reductions of synaptic field potentials by 40-75% by either method at control synapses were accompanied by equivalent reductions at previously potentiated synapses. These results suggest that LTP expression is not due to a change in the curves relating synaptic current to synaptic conductance as would be predicted by the spine resistance hypothesis.

A test of the spine resistance hypothesis for LTP expression

Long-term potentiation (LTP) consists of an enhanced response to released transmitter by the quisqualate/AMPA subclass of glutamate receptors with little change in the slower currents generated by the NMDA receptor subclass. Recent computer simulations suggest that a decrease in the resistance of dendritic spines would selectively augment fast synaptic currents and this could produce the pattern of results found with LTP. The present experiments tested this hypothesis by asking whether non-NMDA responses slowed by low temperature to resemble NMDA responses could express LTP. Slow non-NMDA responses recorded at 25 degrees C did express LTP, indicating that the time courses of NMDA responses cannot explain why they do not express LTP. The results, therefore, do not support the hypothesis that spine resistance changes are responsible for the enhanced transmission.

Development of hippocampal long-term potentiation is reduced by recently introduced calpain inhibitors

The effects of two recently synthesized inhibitors of calpains, calpain inhibitor I (CiI) and calpain inhibitor II (CiII) were tested on the development of long-term potentiation (LTP) in region CA1 of rat hippocampus. Slices maintained in 100 microM of CiI or CiII showed an initial degree of potentiation after theta burst stimulation that, in contrast to controls, slowly decayed across time. The effects of CiI and CiII appeared to be independent of possible actions on the physiological mechanisms that take place during the induction stage of LTP. Since these inhibitors are more potent and specific than leupeptin in blocking calpain activity, their effects on LTP can be more convincingly ascribed to a selective blockade of the calcium-sensitive protease. Accordingly, the results favor the idea that a proteolytic event of the kind found after N-methyl-D-aspartate receptor activation is an intermediary step in the development of LTP.

Recurrent carcinoma of the vulva after conservative treatment for "microinvasive" disease

Although the standard therapy of vulvar carcinoma remains radical surgery, this approach is accompanied by significant postoperative morbidity and psychological adjustment. Radical hemi-vulvectomy and ipsilateral superficial groin node dissection are increasingly used for patients with "early" or "microinvasive" disease. Two patients with an "early" vulvar carcinoma were treated conservatively and later developed recurrent disease. Despite further surgery and radiotherapy, both patients eventually died of disease. The case histories are described and the pertinent literature is discussed.

Extended-field radiation therapy for carcinoma of the cervix

The survival of cervical carcinoma patients with paraaortic/high common iliac nodal metastases was evaluated by retrospective chart review during a 13-year interval. Thirty-three patients with cervical carcinoma and surgically documented nodal metastases received primary, extended-field radiation therapy. Overall 2-year and 5-year actuarial survival rates after diagnosis were 37% and 31%, respectively. Survival was analyzed in terms of the variables patient age, clinical stage, tumor histologic type, the presence of enlarged paraaortic/high common iliac lymph nodes, the extent of nodal involvement (microscopic versus macroscopic), the presence of intraperitoneal disease, and whether intracavitary brachytherapy was administered. The use of intracavitary radiation therapy was associated with improved local control and survival (P = 0.017). None of the other variables were statistically related to patient survival. Twenty-two of the patients died of cervical cancer and five are surviving without evidence of cancer. Four patients died of intercurrent disease. Two patients developed bowel-related radiation complications; both patients received chemotherapy concurrent with the radiation therapy. One of the two patients died of radiation enteritis. The use of extended-field radiation therapy does benefit a small group of patients and may result in extended patient survival.

Identification of a rabies virus T cell epitope on the basis of its similarity with a hepatitis B surface antigen peptide presented to T cells by the same MHC molecule (HLA-DPw4)

The antigenic determinant recognized by a HLA-DPw4-restricted human T cell clone specific for rabies virus was identified by using a vaccinia-rabies nonstructural phosphoprotein recombinant virus and synthetic peptides of the sequence of rabies nonstructural Ag. These peptides were selected on the basis of three models that predict T cell epitopes. The antigenic determinant recognized by the rabies virus-specific T cell clone contained a five-amino acid segment highly homologous to a sequence found in a hepatitis B surface Ag epitope that stimulates human T cells in the context of the HLA-DPw4. A preliminary model of DPw4-restricted T cell determinants is elaborated based on a hypothesis of how the 2 alpha-helical peptides may bind to this MHC molecule. Results are further discussed in the context of the usefulness in identifying DPw4-restricted T cell epitopes for the production of synthetic vaccines because this MHC class II molecule is found with high frequency in the population.

Identification of a rabies virus T cell epitope on the basis of its similarity with a hepatitis B surface antigen peptide presented to T cells by the same MHC molecule (HLA-DPw4)

The antigenic determinant recognized by a HLA-DPw4-restricted human T cell clone specific for rabies virus was identified by using a vaccinia-rabies nonstructural phosphoprotein recombinant virus and synthetic peptides of the sequence of rabies nonstructural Ag. These peptides were selected on the basis of three models that predict T cell epitopes. The antigenic determinant recognized by the rabies virus-specific T cell clone contained a five-amino acid segment highly homologous to a sequence found in a hepatitis B surface Ag epitope that stimulates human T cells in the context of the HLA-DPw4. A preliminary model of DPw4-restricted T cell determinants is elaborated based on a hypothesis of how the 2 alpha-helical peptides may bind to this MHC molecule. Results are further discussed in the context of the usefulness in identifying DPw4-restricted T cell epitopes for the production of synthetic vaccines because this MHC class II molecule is found with high frequency in the population.

A patient with multiple, malignant melanomas of the lower genital tract

Malignant melanomas of the female genital tract are uncommon lesions. A patient with multiple cutaneous, vulvar melanomas and a subsequent malignant melanoma of the cervix is described.

Anoxia reveals a vulnerable period in the development of long-term potentiation

Transient anoxia occurring 1-2 min after high-frequency stimulation selectively prevented the stable expression of long-term potentiation (LTP). Anoxia occurring after this brief vulnerable period did not reverse LTP. Experiments on the duration of anoxia necessary to block LTP expression indicated that simply reducing synaptic transmission was insufficient but that membrane depolarization was not required. The effects of anoxia on LTP were blocked by antagonists of A1 adenosine receptors. It is concluded that LTP develops in about one minute and that the chemistries operating in this period are easily disrupted by an event triggered by adenosine receptors.

Long-term potentiation of monosynaptic EPSPs in rat piriform cortex in vitro

Induction of long-term potentiation (LTP) by burst stimulation patterned after the limbic system theta rhythm was studied in slices of piriform cortex. Monosynaptic responses were evoked by stimulation of afferent fibers of the lateral olfactory tract (LOT) or the intrinsic associational (ASSN) feedback system. LTP was difficult to elicit at LOT synapses in the presence of 2.5 mM extracellular Mg2+, and when it was induced potentiation increased for 20-30 min after burst stimulation before stabilizing. The probability of inducing LTP was increased when the extracellular Mg2+ concentration was reduced to 50 microM. In ASSN synapses LTP developed in about 1 min after burst stimulation and then remained stable. ASSN system LTP was more readily induced in slices from caudal than rostral piriform. Induction of LTP at both LOT and ASSN synapses was blocked by D-2-amino-5-phosphonopentanoate, indicating that NMDA receptor activation was required. Neither system exhibited the decremental short-term potentiation effect observed after burst stimulation of inputs to the CA1 field of hippocampus.

The nature and causes of hippocampal long-term potentiation

One of the most fascinating features of the hippocampus is its capacity for plasticity. Long-term potentiation (LTP), a stable facilitation of synaptic potentials after high-frequency synaptic activity, is very prominent in hippocampus and is a leading candidate memory storage mechanism. Here, we discuss the nature and causes of LTP and relate them to endogenous rhythmic neuronal activity patterns and their potential roles in memory. Anatomical studies indicate that LTP is accompanied by postsynaptic structural modifications while pharmacological studies strongly suggest that LTP is not due to an increase in presynaptic transmitter release. In field CA1, LTP induction appears to be triggered by a postsynaptic influx of calcium through NMDA receptor-linked channels. Possible roles of several calcium-sensitive enzyme systems in LTP are discussed and it is argued that activation of a calcium-dependent protease (calpain) could produce the structural changes linked to LTP. Rhythmic bursting activity is highly effective in inducing LTP and it is argued that the endogenous hippocampal theta rhythm plays a role in LTP induction in vivo. Finally, studies indicate that LTP and certain types of memory share a common pharmacology and the use of electrical brain stimulation as a sensory cue suggests that LTP develops when the significance of that cue is learned.