Developmental and pharmacological analysis of the cardiac response to an acoustic startle stimulus

The purpose of this research was to study the cardiac response of preweanling and adult rats to 10 presentations of an acoustic startle stimulus (0 ms rise time, 100 ms, 130 dB, white noise stimulus). The first presentation of the startle stimulus produced a decrease in heart rate (HR) at both ages. With continued stimulus presentations, the response shifted to tachycardia in the adults but remained bradycardia in the preweanlings. Pharmacological analysis revealed that the startle stimulus activated only the parasympathetic system in the preweanling rats on all 10 trials. In contrast, the startle stimulus produced coactivation of the parasympathetic and sympathetic systems in the adults on the first trial, with the parasympathetic system predominating, and solely sympathetic activation on later trials. These results are discussed in terms of current psychophysiological models of (a) the cardiac response to startle stimuli and (b) autonomic space.

Celebrating New Year in Bart's dissecting room

This paper presents a condensed version of a Victorian story concerning a surreal New Year's social gathering in the dissecting room at St. Bartholomew's Hospital Medical School, London. The story focuses upon the relationship between a medical student and a community of cadavers who come to life for the evening. The ethos of the dissecting room in the nineteenth century as revealed by the tale differs markedly from that of the present day. The story offers a persuasive narrative about the ethical treatment of the dead, and could prove a useful teaching tool. An introduction, discussion, and footnotes accompany the text, to draw out the cultural and moral significance of the original.

A series of 1000 consecutive out-patient diagnostic hysteroscopies

OBJECTIVE

To review the success of out-patient diagnostic hysteroscopy.

METHOD

Retrospective review of 1000 consecutive out-patient hysteroscopies.

RESULTS

Hysteroscopy was successfully performed in 96%. Cervical dilatation was required in 15.0% and local anaesthesia was administered in 31.4%; 77.3% of those requiring cervical dilatation received local anaesthesia. Intrauterine pathology was noted in 49.3%. The procedure failed in 40 (4%) patients for the following reasons: pain or anxiety in 23, cervical stenosis in 11, equipment failure in 4, and extreme uterine retroversion and inadvertent false cavity formation in one case each.

CONCLUSION

Out-patient diagnostic hysteroscopy is a safe, well tolerated and successful investigation procedure in the majority of patients and should be the procedure of choice for suspected intrauterine pathology.

Donors' attitudes towards body donation for dissection

We report a survey in the UK of potential whole-body donors for dissection. 218 people (age range 19-97 years) answered a postal questionnaire, giving information about themselves, their reasons for donation, attitudes towards the dead body, funeral preferences and medical giving and receiving. In addition to altruism, motives included the wish to avoid funeral ceremonies, to avoid waste, and in a few cases, to evade the expense of a funeral. 44% understood that their bodies would be used as teaching material, 42% for experiments. Whilst 69% believed in one or more supernatural phenomena, only 39% said they were religious. 69% requested cremation after dissection; 2% wanted to be buried. The notion of money incentives to promote donation was overwhelmingly rejected.

Humpty Dumpty: reflection and reflective nursing practice

The recent increase in the amount of published work relating reflection and reflective practice to nurses and nursing practice suggests that nurses value the opportunities which this approach is believed to provide. There also appears to be an underlying assumption that we all share the same concepts, hence the association with Humpty Dumpty. Indications of attempts to mechanize the processes and to endow the perceived skills with an élitism are becoming evident. In contrast, there are other attempts to foster the notion of accepting uncertainty, unpredictability and the opportunity for increased understanding to emerge. In this paper, the roots of some of these concepts are traced. The appropriateness of traditional values and assumptions, based on natural science perspectives, in relation to reflective processes and the practice of nursing is questioned. The development of a multi-faceted approach which takes account of differing contexts and the factors which influence them is suggested.

Delayed development of conditioned heart rate responses to auditory stimuli in the rat

This study examined heart rate responses to an auditory conditioned stimulus during development in the rat. The unconditioned stimulus (US) in all experiments was an acoustic startle stimulus. The conditioned stimulus elicited a monophasic bradycardia in animals 21 days of age and older, but no response in younger animals. These results are strikingly similar to an earlier study that used shock as the US (Campbell & Ampuero, 1985). Further, the conditioned cardiac response in adults was found to be mediated entirely through activation of the parasympathetic division of the autonomic nervous system (ANS) even though the US unconditionally activates the sympathetic system at that age. The delayed development of several different forms of conditioned fear is discussed.

Delayed development of fear-potentiated startle in rats

The developmental emergence of fear-potentiated startle was examined in rats ranging in age from 16 to 75 days. In Experiment 1, a pure tone served as the conditioned stimulus (CS) and an acoustic startle pulse served as the unconditioned stimulus (US) for fear conditioning. Fear-potentiated startle by the tone CS was observed in rats 23 days of age and older but not in rats 16 days of age. In Experiment 2, a light served as the CS. Rats 30 days of age and older showed fear-potentiated startle, whereas 23-day-old rats did not. The final experiment demonstrated that another behavioral index of fear, stimulus-elicited freezing, was observed earlier in development than fear-potentiated startle, confirming the effectiveness of the training procedure for conditioning fear. The results suggest that fear-potentiated startle is a relatively late-emerging response system, paralleling the development of conditioned autonomic changes (e.g., heart rate) rather than that of freezing.

The orienting response to brief auditory stimuli in preweanling and adult rats

The cardiac orienting response to brief auditory stimuli was measured in preweanling and adult rats. The eliciting stimulus varied in duration (2 or 10 s) and complexity (continuous or pulsing). Stimulus complexity affected response magnitude with the pulsing stimulus eliciting a larger response than the continuous stimulus. Stimulus duration affected response persistence but only when a pulsing stimulus was used. In contrast to recent research with stimuli of much longer duration, age did not significantly affect any aspect of the cardiac response to the novel auditory stimuli in the present study. These results are discussed in terms of (1) the effects of stimulus duration on the heart-rate component of the orienting response and (2) two-stage models of attention.

Delayed development of fear-potentiated startle in rats

The developmental emergence of fear-potentiated startle was examined in rats ranging in age from 16 to 75 days. In Experiment 1, a pure tone served as the conditioned stimulus (CS) and an acoustic startle pulse served as the unconditioned stimulus (US) for fear conditioning. Fear-potentiated startle by the tone CS was observed in rats 23 days of age and older but not in rats 16 days of age. In Experiment 2, a light served as the CS. Rats 30 days of age and older showed fear-potentiated startle, whereas 23-day-old rats did not. The final experiment demonstrated that another behavioral index of fear, stimulus-elicited freezing, was observed earlier in development than fear-potentiated startle, confirming the effectiveness of the training procedure for conditioning fear. The results suggest that fear-potentiated startle is a relatively late-emerging response system, paralleling the development of conditioned autonomic changes (e.g., heart rate) rather than that of freezing.

Premature atherosclerosis with photomyoclonic epilepsy, deafness, diabetes mellitus, nephropathy, and neurodegenerative disorder in two brothers: a new syndrome?

We describe two brothers with sensorineural deafness, diabetes mellitus, progressive neurological deterioration with photomyoclonic epilepsy, and progressive deterioration in renal function, resulting in death in the third decade of life. Autopsy showed diffuse atherosclerosis and arteriolosclerosis of the systemic vasculature. There was no evidence of these abnormalities in the patients' 2 sisters or either parent. Mitochondrial enzyme analysis documented partial deficiencies of Complex III and IV of the respiratory chain. This deficiency was expressed in skin fibroblasts, kidney and liver but not in muscle. This suggests that the disease-causing mutation is either in the mitochondrial or nuclear DNA. Various modes of inheritance are considered, including maternal, autosomal recessive, or X-linked recessive. We suggest this is a new genetic syndrome characterized by an underlying metabolic disease and premature atherosclerosis, possibly of mitochondrial origin.

Audit of nutritional support provided to surgical patients by a nutrition team

An audit was carried out over a 24 month period to assess the practice, safety and efficacy of nutritional support provided to surgical patients by a designated team. 135 patients received nutritional support: 51% were fed parenterally, 32% enterally and 17% via combined nutritional support. The duration of feeding ranged from 1-177 days with 23% being supported for < 7 days. The line infection rate for patients receiving intravenous nutrition was 6.5%. Nutritional outcome was assessed using weight, anthropometry and bioelectrical impedance analysis. Pre-and post-feeding results were available for 67% of patients. These patients were classified as either oedematous (n = 21), normally nourished (n = 23) or nutritionally depleted (n = 46). Overall, the oedematous patients lost water, the protein status of the normally nourished group deteriorated slightly and the nutritional status of the nutritionally depleted patients was maintained. Audit is a valuable means of defining the efficacy of a nutrition support service and has identified areas which require review.

Management of patients with the Zollinger-Ellison syndrome

The Zollinger-Ellison syndrome, which is due to the secretion of gastrin from non-beta islet cell tumors of the pancreas, results in gastric hypersecretion and severe peptic ulcer disease. In the 1970s H2 blockers became the mainstay of therapy. More recent evidence indicates that early surgical intervention aimed at tumor extirpation results in improved outcome. The purpose of this paper is to report the case histories of three patients with Zollinger-Ellison syndrome and to review the current literature on management of patients with this syndrome.

A Monte Carlo model for retrospective analysis of shield design in a diagnostic x-ray room

Recent recommendations by the NCRP and the ICRP have lowered the nonoccupational dose limit from 5 mSv y-1 to 1 mSv y-1 [corrected]. This change has also been incorporated in the recently revised Title 10 Code of Federal Regulations, Part 20. Shielding installed in most current diagnostic x-ray rooms was based on the 5-mSv limit when rooms or corridors adjacent to the x-ray room were unrestricted areas. A computer model for evaluating shielding in a diagnostic x-ray room has been developed using the following: the Monte Carlo Code MCNP, all materials that would normally attenuate the beam in an x-ray room, realistic assumptions for work load, and a spectrum of tube potentials based on actual usage. Results indicate that most radiographic x-ray rooms with shielding designed using the conservative assumptions in NCRP 49 will meet the new standards.

Extrarenal effect of cyclosporine A on potassium homeostasis in renal transplant recipients

Cyclosporine A (CyA) is known to cause hyperkalemia by impairing renal potassium excretion. However, the observation of transient and severe hyperkalemia occurring within 3 to 5 hours of CyA ingestion in several organ transplant patients led us to postulate that it might also cause a potassium efflux from the intracellular to the extracellular fluid space. We tested this hypothesis by studying 22 nondiabetic, renal transplant patients with stable renal function (serum creatine < 2.25 mg/dL) who were treated with CyA (CyA group; n = 14) or imuran and prednisone (STD group; n = 8). Eight CyA and four STD patients also were treated with a beta-blocker (BB). While at rest, fasting plasma potassium levels were sampled hourly in all patients from 8:00 am to 1:00 pm. All medications (including CyA and BBs) were given after the 8:00 am blood sampling. Venous pH, osmolality, insulin, aldosterone, epinephrine, norepinephrine, and CyA levels also were determined at 8:00 am, 11:00 am, and 1:00 pm. Urine was collected from 11:00 pm to 8:00 am prior to the study (period I) and from 8:00 am to 1:00 pm during the study (period II) for measurement of potassium excretion (standardized to a 5-hour period). A significant increase in serial plasma potassium levels was noted in the CyA + BB group only (P = 0.0006 by repeated measures analysis of variance).(ABSTRACT TRUNCATED AT 250 WORDS)

Reactivation of nonassociative memory

The orienting response to an auditory stimulus, as measured by a decrease in heart rate, habituates rapidly, and at the same rate in preweanling and adult rats. Although adult rats retain this nonassociative memory for at least 7 days, preweanling rats show extremely rapid forgetting. In the preweanling, forgetting of this nonassociative memory appears to be complete after just 24 hr (Richardson & Campbell, 1991b). The results of several experiments in the present study with preweanling rats demonstrated that this type of nonassociative memory could be reactivated by presenting a fractional component of the original eliciting stimulus just prior to testing. The effectiveness of the reactivation treatment was critically dependent upon both the number of reactivating stimuli presented and the duration of those stimuli. Reactivation was also found to be stimulus-specific in that presentation of an auditory stimulus qualitatively different from that used in training (white noise instead of a pure tone) did not reactivate the memory. Control groups in each experiment demonstrated that the reactivation treatment facilitated retrieval of the prior nonassociative memory and did not produce new learning. A possible process through which nonassociative memories can be reactivated is discussed.

Muscular strength capacity and altitude response

To determine the relationship between muscular strength and altitude response, two groups of 7 and 8 subjects were selected from 40 healthy male volunteers, as either high-strength (HS) or low-strength (LS) by performance on a battery of strength tests. There was no difference in hypoxic ventilatory response (HVR) between groups at normobaria. The 4 h hypobaric conditions in a Hypo-hyperbaric Chamber (PBar = 429) produced qualitatively similar altitude-induced physiological responses. However, the LS group showed a lower SaO2 at 2 and 4 h of hypoxia (p < 0.05). Furthermore, PETCO2 and PVCO2 were lower and PETO2, PVO2, and pH were greater in the HS group during hypobaria, although these differences did not achieve statistical significance. Muscular strength index (body weight divided by strength test values) was negatively correlated with PvCO2 (r = -0.63, p = 0.0074), PETCO2 (r = -0.62, p = 0.006) and positively with SaO2 (r = 0.54, p = 0.018) at altitude. These findings suggest that the HS group may have become more hypocapnic and alkalotic (suggesting a greater ventilatory response), and consequently less hypoxic than the LS group.

Neurologic consequences of cerebrovascular injury

Because of ongoing controversy, the issue of vascular repair or ligation for patients with cerebrovascular injuries and preoperative central neurologic deficits is frequently debated. A total of 133 patients with penetrating cerebrovascular injuries were analyzed. The frequency of preoperative neurologic deficit was 20% (27 patients). The common carotid and internal carotid arteries were the most frequently injured structures, with a 29% and 15% incidence of preoperative neurologic deficits, respectively. The results of carotid repair in all patients whose preoperative deficit was limited to weakness or paralysis were favorable (seven patients normal or improved, two patients unchanged). The results of repair in patients whose preoperative deficit was characterized by obtundation were variable (four patients improved, four patients worsened or died). The results of carotid ligation were also variable (one improved, one unchanged, three worsened or died). Limited numbers of patients with preoperative neurologic deficits and the retrospective nature of this review prohibit definite conclusions. Therefore a multicenter, prospective, randomized trial of ligation or vascular repair for comatose patients with cerebrovascular injuries is proposed.