Tobacco intolerance in multiple system atrophy.

In a patient with multiple system atrophy, the ataxia was temporarily exacerbated by cigarette smoking. The phenomenon is attributed to a direct effect of nicotine on the central nervous system, rather than being secondary to autonomic changes. Its prevalence and specificity are currently unknown.

Differential cholinergic sensitivity of sinus and AV nodes.

The effects of the muscarinic antagonist gallamine were studied in anesthetized dogs via selective perfusion of the SA and AV nodal arteries. Before gallamine, acetylcholine injected into the SA node artery induced asystole while injection into the AV node artery induced heart block. After gallamine, acetylcholine via the AV node artery was without effect while, via the SA node artery, acetylcholine still induced negative chronotropic effects. Thus the muscarinic receptors of the SA and AV nodes may be inhomogeneous.

Assessing the impact of community-based mobile crisis services on preventing hospitalization.

OBJECTIVE: This study evaluated the impact of a community-based mobile crisis intervention program on the rate and timing of hospitalization. It also explored major consumer characteristics related to the likelihood of hospitalization. METHODS: A quasi-experimental design with an ex post matched control group was used. A community-based mobile crisis intervention cohort (N=1,696) was matched with a hospital-based intervention cohort (N=4,106) on seven variables: gender, race, age at the time of crisis service, primary diagnosis, recency of prior use of services, indication of substance abuse, and severe mental disability certification status. The matching process resulted in a treatment group and a comparison group, each consisting of 1,100 subjects. Differences in hospitalization rate and timing between the two groups were assessed with a Cox proportional hazards model. RESULTS: The community-based crisis intervention reduced the hospitalization rate by 8 percentage points. A consumer using a hospital-based intervention was 51 percent more likely than one using community-based mobile crisis services to be hospitalized within the 30 days after the crisis (p<.001). Treating a greater proportion of clients in the community rather than hospitalizing them did not increase the risk of subsequent hospitalization. Those most likely to be hospitalized were young, homeless, and experiencing acute problems; they were referred by psychiatric hospitals, the legal system, or other treatment facilities; they showed signs of substance abuse, had no income, and were severely mentally disabled. CONCLUSIONS: Results indicate that community-based mobile crisis services resulted in a lower rate of hospitalization than hospital-based interventions. Consumer characteristics were also associated with the risk of hospitalization.

An exploratory study of patient attitudes towards symptom reporting in a primary care setting. Benefits for medical consultation and syndromic surveillance?

OBJECTIVES: The aim of this study was to investigate people's attitude towards providing symptom information electronically before a consultation. Specific areas investigated include a) attitudes and experiences with regards to acquisition of information related to symptoms, b) attitudes towards computer based communication of symptoms to the general practitioner and how they preferred to carry out such reporting, and c) attitudes towards storage, use and presentation of symptom-data in general, and particularly in a symptom based surveillance setting. METHODS: Data was collected from 83 respondents by use of convenience sampling. RESULTS: The respondents were familiar with using the Internet for health purposes, such as acquisition of information related to their symptoms prior to a consultation. The majority of respondents had a positive attitude towards providing information about their symptoms to the general practitioner's office as soon as possible after falling ill. Over half of the respondents preferred to use e-mail or a web-interface to perform this task. Eighty four percent were willing to have their symptom data stored in their EPR and 76 percent agreed that the general practitioner might access the symptoms together with the prevalence of matching diseases in order to assist the diagnostic process during the next consultation. CONCLUSIONS: The results of this study support the applicability of electronically mediated pre-consultation systems both for improving primary care consultation and for use in symptom based surveillance, including real-time surveillance.

Detection of parts in patterns and images.

Subjects performed in an embedded-figures detection task which required them to judge whether one pattern was a part of another. In the perception condition, the part was presented before the complete pattern, but in the imagery condition, the part was presented after the complete pattern. Subjects made fast, but inaccurate, responses in the perception task when RT s were recorded, but the error rate declined substantially when they were given 10 sec to make a decision. In the latter condition, subjects failed to detect a part on 14% of the trials in the perception condition and on 72% of the trials in the imagery condition when a correction was made for prior perception of the part. A subsequent experiment showed that the high error rate in the imagery task was not the result of the subject's inability to remember the complete pattern. The complexity of mental operations and the limited accuracy of visual images are considered as possible alternative explanations of the results.

Lymphatogenous spread of renal cell carcinoma: an autopsy study.

PURPOSE: We investigated the occurrence and extent of metastatic spread, especially regarding lymph nodes, of renal cell carcinoma. MATERIALS AND METHODS: From 1958 to 1982, 554 cases of renal cell carcinoma were diagnosed at autopsy. Clinical data and autopsy findings were reevaluated, and the occurrence of lymph node metastases was analyzed by histological examination of retroperitoneal, mediastinal, supraclavicular, axillary and inguinal lymph nodes. RESULTS: Distant metastases were revealed in 119 cases (21.5%), including 31 (5.6%) with single metastases. In 88 cases (16%) renal cancer was the cause of death. Lymphatogenous dissemination was detected in 80 cases of which 75 had additional, mostly multifocal metastatic spread. Consequently lymph node metastases restricted to the paracaval and/or para-aortic lymph nodes were noted in only 5 cases (0.9%). CONCLUSIONS: Of the 554 cases of clinically unrecognized renal cell carcinoma almost all with lymphatic spread had additional distant metastases. Therefore, the therapeutic effect of extensive retroperitoneal lymph node dissection in association with radical nephrectomy seems to be low. However, more limited lymph node dissection may be useful, mainly as a staging procedure.

Correlation of activity in neighbouring goldfish ganglion cells: relationship between latency and lag.

Pairs of retinal ganglion cells in the isolated goldfish retina were recorded simultaneously with a single electrode. Repeated flashes of light were delivered to evaluate the response latency of each of the units. The cross-correlation histogram for the maintained discharge of each pair of cells was examined, and its temporal relationships (lags) were compared with the differences in response latencies of the two units. There was a strong correlation between these measures; however, the differences between latencies were often at least twice as great as the lags. The differences between the times to the peaks of the responses of the two units were less reliably related to the lags of the pairs, although the correlation was positive and the differences in time-to-peak generally greater than the lags. The weaker relationship between the difference in time-to-peak and lag than between latency difference and lag is apparently a manifestation of a negative correlation between latency and rise time (from first response to peak). This indicates that cells with a longer latency compensate with a faster rise time. There was a negative correlation between the mean maintained rate of a neurone and its response latency. That is, cells with faster maintained discharge rates respond sooner than those with slower maintained rates. There was virtually no relationship between the lags or the differences in latency and the differences between the magnitudes of the responses to light. Thus, it is unlikely that differences in latency (or lags) could be attributed to unequal effectiveness of the stimuli for the two units. The relationship between differences in latency and lags did not depend on the response categorizations of the two units. Specifically, it did not matter whether the members of the pair were on centre, off centre or on-off centre; neither did it matter whether they were X-like or not-X-like neurones. Consideration of these data leads to the conclusion that there must be 'marked' pathways of differential conduction velocity through the retina.

Common noise in the firing of neighbouring ganglion cells in goldfish retina.

Pairs of goldfish retinal ganglion cells with overlapping receptive fields were recorded during stimulation with repeated light flashes. Cross-correlation histograms for 'maintained' discharge, 'on' responses, and 'off' responses were computed with a correction for the systematic responses to the stimuli; cross-covariances were derived from these. If stimulus-induced signals and noise combine linearly, then the cross-covariances are independent of differences in mean firing rate. Cross-covariances of pairs of cells with the same response polarity displayed a positive peak near zero lag; pairs with complementary responses showed a negative peak. 'On-off' cells could generally be classified as on-like or off-like, based on the plateau of firing during a prolonged flash and the relative magnitudes of the on and off peak responses; the cross-covariances of these cells were as one would predict if they were pure on- or off-centre neurones. The cross-covariances derived from the on period usually differed in magnitude from those derived in the dark (either maintained or off response). In general, cross-covariances for off responses were nearly identical to those for the maintained discharges of the same pair, although the mean rates at off were usually quite different from the maintained. The change in magnitude of the cross-covariances from on responses therefore appears to be a non-linear effect of light, and not of the changes in firing rate induced by the light. Other features of the cross-covariances were not affected by stimulation. The general shapes remained fairly constant, and the lags at which the peaks occurred were not consistently affected. We estimated the variance of the firing rate of each unit in three ways, and used two methods of portioning the variance implied by the cross-covariances; from these estimates, we obtained an upper bound for the proportion of the variance of firing of a cell which is due to the common noise that affects both members of a pair. We found that the common influence accounts for less than 20% of the total variance. During stimulation, both the magnitude of the cross-covariance and the variance of the rates change; however, the percentage of total variance contributed by the common noise source is constant. We conclude that light has the effect of changing the gain of the pathway after the introduction of both the common and unshared (private) noise sources but before the ganglion cell.(ABSTRACT TRUNCATED AT 400 WORDS)

Postvagal potentiation of the chronotropic effect of norepinephrine.

Following termination of vagal stimulation, heart rate increases above control (postvagal tachycardia). This phenomenon has been attributed to vagally mediated release of norepinephrine in the sinus node region, although other contributory factors may be important. The possibility that, during the postvagal period, the chronotropic efficacy of norepinephrine is enhanced was investigated. Mongrel dogs (N = 6) were pretreated with reserpine in order to minimize postvagal tachycardia and hence allow reliable detection of enhanced responsiveness to norepinephrine. The dogs were then anesthetized with chloralose, autonomically decentralized, and instrumented to record electrocardiogram, aortic blood pressure, and electrograms from right atrium and right ventricle. Thirty-, forty-, or sixty-second infusions of norepinephrine were administered via the sinus node artery. The mean cycle length decrease produced by norepinephrine alone was 95 msec (which corresponds to a heart rate increase of + 19.6 bpm). After a 30-sec period of vagal stimulation, norepinephrine infusions produced a cycle length decrease of 139 msec (+32.5 bpm). These results are significant at the P less than 0.05 level. It is concluded that norepinephrine infusions produce a significantly greater magnitude of tachycardia when administered postvagally. It is proposed that this postvagal potentiation of the chronotropic effect of norepinephrine may contribute to postvagal tachycardia. Indeed, there may be a synergistic relationship between this phenomenon and vagally mediated release of norepinephrine in the mediation of postvagal tachycardia.