Species-specific responses of N homeostasis and electrolyte handling to low N intake: a comparative physiological approach in a monogastric and a ruminant species.

In our former studies low crude protein (LCP) intake influenced N homeostasis and electrolyte handling in goats. We hypothesised that due to rumino-hepatic nitrogen (N) recycling adaptation of N homeostasis and adjustment of electrolyte handling to LCP intake differs between goats and monogastric animals. Therefore, an experiment similar to that with goats was conducted with rats. Two feeding groups received a diet either containing 20 or 8 % crude protein (as fed basis) for 5 weeks and intake and excretion of N, calcium (Ca) and phosphorus (P) were determined. To detect systemic and endocrine adaptation to LCP intake plasma concentrations of urea, Ca, phosphate (Pi), insulin-like growth factor 1 (IGF-1), 1,25-dihydroxyvitamin D3 (calcitriol), parathyroid hormone (PTH) and cross-linked telopeptide of type I collagen (CTX) were measured. Adjustment of renal electrolyte transport was assessed by detecting protein expression of key proteins of renal Pi transport. All data were compared with the data of the goat experiment. LCP intake decreased plasma urea concentration stronger in goats than in rats. In both species urinary N excretion declined, but faecal N excretion decreased in goats only. Furthermore, in goats urinary Ca excretion decreased, but in rats urinary Ca concentration increased. Decreased plasma IGF-1 and calcitriol concentrations were found in goats only. Thus, renal Ca excretion appears to be a common target in adaptation of electrolyte homeostasis in both species, but is regulated differently.

Cell's intrinsic biophysical properties play a role in the systematic decrease in time-locking ability of central auditory neurons.

Studies in the vertebrates have shown that the time-locking ability of central auditory neurons decreases progressively along the ascending auditory pathway. This decrease is presumably attributed to a progressive reduction in the fidelity of synaptic transmission and an increase in the influence of synaptic inhibition along the cascade. The extent to which neurons' intrinsic biophysical properties contribute to the change in time-locking ability is unclear. We carried out whole-cell patch clamp recordings from the auditory thalamus of leopard frogs and compared their biophysical properties and time-locking abilities (determined by cell's responses to depolarizing pulse trains applied intracellularly) with those of lower auditory brainstem neurons. We found that frog thalamic neurons were homogeneous, exhibiting uniformly sustained, regular firing patterns, but not having low-threshold transient Ca2+ current which mammal thalamic neurons generally possess. Furthermore, intrinsic biophysical properties of the thalamic neurons are such that the time-locking ability of these neurons was very poor. The homogeneity of thalamic auditory neurons is in contrast to the heterogeneity of lower auditory brainstem neurons, with different phenotypes exhibiting different time-locking abilities and with sustained-regular phenotype consistently showing the worst time-locking ability among all biophysical phenotypes. Auditory nuclei along the ascending auditory pathway showed a progressive increase in the population of sustained-regular phenotype-this corresponded to a systematic decrease in the overall time-locking ability, with neurons in the dorsal medullary nucleus showing the best, and thalamic neurons exhibiting the poorest time-locking ability, whereas neurons in the torus semicircularis displayed intermediate time-locking ability. These results suggest that the biophysical characteristics of single neurons also likely play a role in the change in temporal coding ability along the ascending auditory pathway.

Dopamine enhances the excitability of somatosensory thalamocortical neurons.

The thalamus conveys sensory information from peripheral and subcortical regions to the neocortex in a dynamic manner that can be influenced by several neuromodulators. Alterations in dopamine (DA) receptor function in thalami of Schizophrenic patients have recently been reported. In addition, schizophrenia is associated with sensory gating abnormalities and sleep-wake disturbances, thus we examined the role of DA on neuronal excitability in somatosensory thalamus. The ventrobasal (VB) thalamus receives dopaminergic innervation and expresses DA receptors; however, the action of DA on VB neurons is unknown. In the present study, we performed whole cell current- and voltage-clamp recordings in rat brain slices to investigate the role of DA on excitability of VB neurons. We found that DA increased action potential discharge and elicited membrane depolarization via activation of different receptor subtypes. Activation of D2-like receptors (D(2R)) leads to enhanced action potential discharge, whereas the membrane depolarization was mediated by D1-like receptors (D(1R)). The D(2R-mediated) increase in spike discharge was mimicked and occluded by α-dendrotoxin (α-DTX), indicating the involvement of a slowly inactivating K(+) channels. The D1R-mediated membrane depolarization was occluded by barium, suggesting the involvement of a G protein-coupled K(+) channel or an inwardly rectifying K(+) channel. Our results indicate that DA produces dual modulatory effects acting on subtypes of DA receptors in thalamocortical relay neurons, and likely plays a significant role in the modulation of sensory information.

The effect of transcatheter injections on cell viability and cytokine release of mononuclear cells.

BACKGROUND AND PURPOSE: Several studies suggest that various types of cellular therapies enhance recovery after stroke in animal models. IA-based delivery of cells to the brain is under investigation for stroke, but it is unknown whether cells are injured as a result of being injected through a catheter or exposed to iodinated contrast medium or solutions containing heparin. MATERIALS AND METHODS: We assessed the effect of catheterization with the Excelsior SL-10 catheter or exposure to heparin or iodine contrast on human bone marrow MNCs. Viability and cell injury were assessed by trypan blue exclusion, caspase-3 activity, and lipid peroxidation. Cellular function of MNCs was assessed by their production and release of VEGF, IL-10, and IGF-1. RESULTS: Flow rates of 10 million cells from 0.5 to 2 mL/min did not alter MNC viability; however, 5 mL/min of MNCs did reduce viability by 19%. Iodine and low-dose heparin exposure did not affect cell viability; however, high-dose heparin was cytotoxic. Catheter delivery at 2 mL/min did not affect levels of VEGF, IL-10, or IGF-1. CONCLUSIONS: MNCs do not appear to be damaged by heparin, iodine contrast, and the Excelsior SL-10 catheter at flow rates up to 2 mL/min. However, higher flow rates did reduce viability, and high-dose heparin did cause cell death.

Controversial topics in breast lymphatic mapping.

As a result of increased accuracy of staging and decreased patient morbidity, lymphatic mapping and sentinel lymph node (SLN) biopsy for breast cancer has enjoyed a rapid acceptance into clinical practice. Despite the use of lymphatic mapping techniques to obtain nodal staging information, many controversies remain. We have attempted to highlight the major controversies in this report.

Porphyromonas endodontalis binds, reduces and grows on human hemoglobin.

Porphyromonas endodontalis is a black-pigmented, obligate anaerobic rod-shaped bacterium implicated as playing a major role in endodontic infections. We have previously shown that P. endodontalis requires the porphyrin nucleus, preferably supplied as hemoglobin, as a growth supplement. The bacteria also actively transport free iron, although this activity does not support growth in the absence of a porphyrin source. The purpose of this study was to further investigate the binding and subsequent utilization of human hemoglobin by P. endodontalis. P. endodontalis binds hemoglobin and reduces the Fe(III) porphyrin, resulting in a steady accumulation of ferrous hemoglobin. Reduction of methemoglobin was similar to the extracellular reduction of nitrobluetetrazolium in the presence of oxidizable substrate. Turbidimetric and viable cell determinations showed that P. endodontalis grew when supplied only hemoglobin. Therefore, we conclude that hemoglobin appears to serve as a sole carbon and nitrogen source, and that these bacteria reduce extracellular compounds at the expense of oxidized substrates.

The effects of postinjection massage on the sensitivity of lymphatic mapping in breast cancer.

BACKGROUND: The technique of lymphatic mapping and sentinel lymph node (SLN) biopsy is rapidly becoming the preferred method of staging the axilla of the breast cancer patient. This report describes the impact of postinjection massage on the sensitivity of this surgical technique. STUDY DESIGN: Lymphatic mapping at the H Lee Moffitt Cancer Center is performed using a combination of isosulfan blue dye and Tc99m labeled sulfur colloid. Data describing the rate of SLN identification and the node characteristics from 594 consecutive patients were calculated. Patients who received a 5-minute massage after injection of blue dye and radiocolloid were compared with a control group in which the patients did not receive a postinjection massage. RESULTS: When compared with controls, the proportion of patients who had their SLN identified using blue dye after massage increased from 73.0% to 88.3%, and the proportion of patients who had their SLN identified using radiocolloid after massage increased from 81.7% to 91.3%. The overall rate of SLN identification increased from 93.5% to 97.8%. The proportion of nodes that were stained blue among those removed increased from 73.4% to 79.7% after massage. CONCLUSIONS: As experience increases with this new procedure, the surgical technique of lymphatic mapping continues to evolve. The addition of a postinjection massage significantly improves the uptake of blue dye by SLNs and may also aid in the accumulation of radioactivity in the SLNs, further increasing the sensitivity of this procedure.

Dynamics of low-threshold spike activation in relay neurons of the cat lateral geniculate nucleus.

The low-threshold spike (LTS), generated by the transient Ca(2+) current I(T), plays a pivotal role in thalamic relay cell responsiveness and thus in the nature of the thalamic relay. By injecting depolarizing current ramps at various rates to manipulate the slope of membrane depolarization (dV/dt), we found that an LTS occurred only if dV/dt exceeded a minimum value of approximately 5-12 mV/sec. We injected current ramps of variable dV/dt into relay cells that were sufficiently hyperpolarized to de-inactivate I(T) completely. Higher values of dV/dt activated an LTS. However, lower values of dV/dt eventually led to tonic firing without ever activating an LTS; apparently, the inactivation of I(T) proceeded before I(T) could be recruited. Because the maximum rate of rise of the LTS decreased with slower activating ramps of injected current, we conclude that slower ramps allow increasing inactivation of I(T) before the threshold for its activation gating is reached, and when the injected ramps have a sufficiently low dV/dt, the inactivation is severe enough to prevent activation of an LTS. In the presence of Cs(+), we found that even the lowest dV/dt that we applied led to LTS activation, apparently because Cs(+) reduced the K(+) "leak" conductance and increased neuronal input resistance. Nonetheless, under normal conditions, our data suggest that there is neither significant window current (related to the overlap of the inactivation and activation curves for I(T)), rhythmogenic properties, nor bistability properties for these neurons. Our theoretical results using a minimal model of LTS excitability in these neurons are consistent with the experimental observations and support our conclusions. We suggest that inputs activating very slow EPSPs (i.e., via metabotropic receptors) may be able to inactivate I(T) without generating sizable I(T) and a spurious burst of action potentials to cortex.

Attitudes and beliefs about exercise among elderly African Americans in an urban community.

Older African Americans are less likely to exercise compared with their white counterparts. Few studies have examined the facilitating factors and barriers to exercise among older African Americans living in urban communities. This study represented the first phase of a program to develop an exercise intervention in an urban community. Qualitative research was conducted to identify culturally determined attitudes that could be useful in designing an effective exercise program. Five focus groups involving 38 persons from a variety of settings were facilitated by trained professionals. Transcripts were analyzed to identify themes and contrasts among group participants. Contrary to the expectations of the investigative team, focus-group participants: (1) uniformly preferred group exercises compared with exercising at home, (2) rejected walking as a feasible option because of safety concerns, and (3) expressed limited interest in using weights or Eastern exercises such as Tai Chi. Concepts and goals of exercise differed according to the physical capabilities of the participants. The analysis of these focus-group discussions provided valuable insights with regard to the development of our community-based exercise-intervention protocol. These findings may be important in designing effective exercise programs for older African Americans in urban settings.

Cellular mechanisms underlying activity patterns in the monkey thalamus during visual behavior.

We show for the first time with in vitro recording that burst firing in thalamic relay cells of the monkey is evoked by activation of voltage-dependent, low threshold Ca(2+) spikes (LTSs), as has been described in other mammals. Due to variations in LTS amplitude, the number of action potentials evoked by an LTS could vary between 1 and 8. These data confirm the presence of two modes of firing in the monkey for thalamic relay cells, tonic and burst, the latter related to the activation of LTSs. With these details of the cellular processes underlying burst firing, we could account for many of the firing patterns we recorded from the lateral geniculate nucleus of the thalamus in behaving monkeys. In particular, we found clear evidence of burst firing during alert wakefulness, which had been thought to occur only during sleep or certain pathological states. This makes it likely that the burst firing seen in awake humans has the same cellular basis of LTSs, and this supports previous suggestions that burst firing represents an important relay mode for visual processing.

A community pediatric prevention partnership: linking schools, providers, and tertiary care services.

Integrated school health services traditionally have been provided through the local board of education or health department. However, increased competitiveness in the health care arena has challenged providers to find innovative models to deliver health services to school-aged children. This article describes a partnership among a hospital, a university, private providers, and a local school system and health department to provide school health services. Noteworthy aspects of the project include the organizational structure and funding of the program, implementation of a case management model, and a focus on documenting outcomes. This program has been successful in building local alliances to provide health care services to school children. Implications for other school systems struggling to fund health services for school-aged children are discussed.

An evaluation of the management of patients with sore throats by practice nurses and GPs.

BACKGROUND: Practice nurses are increasingly involved in the management of minor illnesses in primary care. However, there has been little work published that evaluates the quality of the service they offer to patients. In our practice (semi-rural, 14,000 patients) a nursing triage system for minor illnesses has been established since 1992. AIM: To compare the quality of management of sore throats by practice nurses and general practitioners (GPs) in a routine nursing triage system. METHOD: An observational study assessing all patients over the age of two years presenting over a six-month period (February-August 1997) to either the practice nurse or GP with a sore throat as the chief presenting complaint. Patients were followed up at five to seven days by a researcher and recovery rates, analgesic requirements, reconsultation rates, and satisfaction rates were recorded. Patients who were still symptomatic at five to seven days were followed up again at 28 days and outcomes recorded. RESULTS: A total of 44% of patients consulted the practice nurse and 56% consulted the GP. Severity of presenting illness was similar in the two groups. The number of patients whose sore throats had settled, reconsultation rates, antibiotic prescription, and dissatisfaction rates were the same for both groups. However, the patients consulting the nurse had a more favourable outcome on indices such as patients' perception of being back to normal health (64% versus 53%) and median number of days for the sore throat to settle (four versus five). Nurses tended to see younger patients (mean age = 22.5 years versus 28.3 years) and more patients seeing the practice nurse recalled receiving advice about home remedies (76% versus 54%). CONCLUSION: Practice nurses can establish a safe and effective service for treatment of sore throats in a time-restricted triage system.

Immediate effects of a five-minute foot massage on patients in critical care.

Critical care can be considered to be a stressful environment at both physiological and psychological levels for patients. In this article, a research study in which a five-minute foot massage was offered to 25 patients (68 sessions in total) as a stress-reduction intervention is described. A quasi-experimental repeated measures design was used to collect data before, during and after the intervention. Physiological data (heart rate, mean arterial blood pressure, respirations and peripheral oxygen saturation) were obtained from the patient bedside monitoring system. Repeated measures analysis of variance indicated there was no significant effect from the intervention on peripheral oxygen saturation. However, a significant decrease in heart rate, blood pressure and respirations was observed during the foot massage intervention. Results indicated foot massage had the potential effect of increasing relaxation as evidenced by physiological changes during the brief intervention administered to critically ill patients in intensive care.

Comparison of the scope of allopathic and osteopathic medical school health promotion programs for students.

PURPOSE: To compare the number and scope of health promotion programs for students in allopathic and osteopathic medical schools in the U.S. and Canada. DESIGN: A one-time cross-sectional survey design was applied in this study. SETTING: This study was conducted in 141 accredited allopathic and 17 accredited osteopathic medical schools. SUBJECTS: A total of 158 representatives from the allopathic and osteopathic medical schools participated in this study. The response rate for the survey was 100%. MEASURES: A structured telephone interview was conducted to survey representatives from the medical schools. The survey contained 85 multiple-choice questions organized into four sections: administrative characteristics, types of institutional and health promotion program policies, participation incentives and facilities, and type/scope of health promotion program activities. Chi-square analysis was used to analyze survey variables by type of medical education and level of intervention. RESULTS: Of the 158 medical schools, only 20% (n = 32) provided a health promotion program for students. Although osteopathic institutions (29.4%) had a greater percentage of programs than allopathic schools (19.2%), there was no significant difference in scope of program offerings by type of medical education. Allopathic programs offered exercise and nutrition/weight management significantly more often and at a higher level of intervention. Lastly, allopathic programs had significantly more monetary resources available for programming. Following prudent research protocol, investigators should be mindful of the limitations of this study. In this study, some school representatives chose not to answer personnel- and finance-related questions. Additionally, because of the self-report nature of the survey, the responses given to the questions may not have been accurate. CONCLUSION: Allopathic and osteopathic medical school health promotion programs for students were very similar in scope.

Current clamp and modeling studies of low-threshold calcium spikes in cells of the cat's lateral geniculate nucleus.

Current clamp and modeling studies of low-threshold calcium spikes in cells of the cat's lateral geniculate nucleus. All thalamic relay cells display a voltage-dependent low-threshold Ca2+ spike that plays an important role in relay of information to cortex. We investigated activation properties of this spike in relay cells of the cat's lateral geniculate nucleus using the combined approach of current-clamp intracellular recording from thalamic slices and simulations with a reduced model based on voltage-clamp data. Our experimental data from 42 relay cells showed that the actual Ca2+ spike activates in a nearly all-or-none manner and in this regard is similar to the conventional Na+/K+ action potential except that its voltage dependency is more hyperpolarized and its kinetics are slower. When the cell's membrane potential was hyperpolarized sufficiently to deinactivate much of the low-threshold Ca2+ current (IT) underlying the Ca2+ spike, depolarizing current injections typically produced a purely ohmic response when subthreshold and a full-blown Ca2+ spike of nearly invariant amplitude when suprathreshold. The transition between the ohmic response and activated Ca2+ spikes was abrupt and reflected a difference in depolarizing inputs of <1 mV. However, activation of a full-blown Ca2+ spike was preceded by a slower period of depolarization that was graded with the amplitude of current injection, and the full-blown Ca2+ spike activated when this slower depolarization reached a sufficient membrane potential, a quasithreshold. As a result, the latency of the evoked Ca2+ spike became less with stronger activating inputs because a stronger input produced a stronger depolarization that reached the critical membrane potential earlier. Although Ca2+ spikes were activated in a nearly all-or-none manner from a given holding potential, their actual amplitudes were related to these holding potentials, which, in turn, determined the level of IT deinactivation. Our simulations could reproduce all of the main experimental observations. They further suggest that the voltage-dependent K+ conductance underlying IA, which is known to delay firing in many cells, does not seem to contribute to the variable latency seen in activation of Ca2+ spikes. Instead the simulations indicate that the activation of IT starts initially with a slow and graded depolarization until enough of the underling transient (or T) Ca2+ channels are recruited to produce a fast, "autocatalytic" depolarization seen as the Ca2+ spike. This can produce variable latency dependent on the strength of the initial activation of T channels. The nearly all-or-none nature of Ca2+ spike activation suggests that when a burst of action potentials normally is evoked as a result of a Ca2+ spike and transmitted to cortex, this signal is largely invariant with the amplitude of the input activating the relay cell.

Single-dose oral ciprofloxacin compared with cefotaxime and placebo for prophylaxis during transurethral surgery.

To determine the efficacy and safety of single-dose oral ciprofloxacin prophylaxis for the prevention of post-operative bacteriuria following transurethral resection of the prostate or bladder tumour, a prospective, randomized, double-blind, placebo-controlled trial was conducted. Five hundred and eighteen patients were randomized in a 2:2:1 ratio to receive ciprofloxacin 500 mg, cefotaxime 1 g or placebo 30-90 min before surgery. Of the 368 efficacy-evaluable patients, five (3.3%) ciprofloxacin, seven (4.8%) cefotaxime and five (7.0%) placebo recipients had post-operative bacteriuria (> or = 10(4) cfu/mL) during post-operative days 2-15. Five (3.4%) ciprofloxacin, five (3.4%) cefotaxime and one (2.4%) placebo recipients were considered clinical failures, of whom one, two and one patients, respectively, had concomitant bacteriuria. Drug-related adverse events were reported in six of 204 (3%) ciprofloxacin, 12 of 197 (6%) cefotaxime and one of 101 (1%) placebo patients. The observed rates of post-operative bacteriuria suggest that a single 500 mg dose of ciprofloxacin is suitable prophylaxis for transurethral surgery.

Physiologic and psychodynamic responses to the administration of therapeutic touch in critical care.

Recent publications have questioned the efficacy of therapeutic touch (TT). The focus of attention has been on substantiating the existence of the recipient's energy field rather than on the physiologic and psychodynamic responses to TT. In this article the physiologic and psychodynamic responses during and following the administration of TT is described. The project involved the implementation of a time series design in which the physiologic and psychodynamic responses were measured. It is acknowledged that critical care environments are stressful for patients in terms of invasive medical and nursing procedures. Continuous bright lighting, and excessive noise prohibits the potential for relaxation and sleep. Within this context, the control of confounding variables was not possible, and therefore not an object of concern in the study. Rather the responses to TT in the natural setting were of importance to discern. Statistical repeated measures analysis of variance (one way) indicated there was no significant difference between pre-, during and post-physiologic variables in response to TT. However psychodynamic responses demonstrated significant correlation's in terms of relaxation and sleep. The non significance of physiologic change in variables pre-, during and post-administration of TT indicates critically ill patients remained physiologically stable. Significant correlations of psychodynamic responses demonstrated it is possible for critically ill patients to experience periods of relaxation and sleep in an otherwise stressful environment. TT was found to be a useful therapy to enhance relaxation and sleep in critically ill patients.

The integration of complementary therapies in North and South Thames Regional Health Authorities' critical care units.

Subsequent to the rising interest in complementary therapies, a survey was conducted to determine the extent of integration of complementary therapies in critical care units in the North and South Thames Regional Health Authorities in the Greater London area. In total, 45 critical care units were surveyed at random. The results of the survey indicated Neonatal Intensive Care Units showed the greatest interest and provision (75%) of complementary therapies. This was primarily in the application of baby massage. In contrast, only 10% of Coronary Care Units surveyed provided complementary therapies. Results further indicated that of 51.1% of critical care units which claimed to provide complementary therapies, only 7% provided interventions on a routine, systematic basis.

The experience of therapeutic touch from a nursing perspective.

This article describes the phenomenon of therapeutic touch (TT). Similarities and differences in the experience of the phenomenon from the perspective of a novice practitioner and healthy volunteers are highlighted. A qualitative analysis of findings indicates that the experiences of giving and receiving TT can be classified within two categories: the cognitive (knowing in the widest sense); and conative (instinct and feeling). The key constructs which emerged in this study are associated with feelings such as tingling, warmth, coolness, comfort, peace, calm and security. Formulation of the two main categories, cognitive and conative, emphasize the relationship associated with what is known by the mind and instinctively felt by the body. The holistic aspects associated with the phenomenon of TT are confirmed in the therapeutic relationship which can be formed between the practitioner and recipient during the administration of TT. It is suggested that TT, when provided by the nurse in the clinical setting, can promote feelings of comfort, peace, calm and security among patients.

Experiences of administering and receiving therapeutic touch in intensive care.

This article describes the experiences of a practitioner who administered therapeutic touch (TT) to two patients in an intensive care unit and the experiences of the two patients who received TT. The experiences are presented as two case studies. Each of the patients presented in the case studies received either five or ten treatments of TT lasting five minutes each. Following each administration of TT the practitioner described what she sensed verbally and in writing. However, owing to the medical conditions of the patients, only brief interviews were conducted in which the patients were asked to describe their experiences of receiving TT. The experiences, which have been reflected in the case studies, indicate TT assists patients to relax, brings comfort and a sense of peace. Much like meditation, TT helps patients become more in touch with themselves. They come to understand more about themselves and reality. TT is recommended as a practice which could contribute to the psychological well-being of patients in intensive care as it promotes relaxation, comfort and a sense of peace.