Intraoperative asystole associated with fibroid uterus.

The authors present the case of a patient with a large retroperitoneal fibroid whose laparotomy was abandoned due to intraoperative asystole. Perioperative management and possible etiological factors are discussed in this paper.

Major pelvic fractures: identification of patients at high risk.

The identification of high-risk factors in patients with fractures of the pelvis at the time of presentation would facilitate investigation and management. In a series of 174 consecutive patients with unstable fractures of the pelvic ring, clinical data were used to calculate the injury severity score (ISS), the triage-revised trauma score (T-RTS), and the Glasgow coma scale (GCS). The morphology of the fracture was classified according to the AO system and that of Burgess et al. The data were analysed using univariate and multivariate methods in order to determine which presenting features were identified with high risk. Univariate analysis showed an association between mortality and an ISS over 25, a T-RTS below eight, age over 65 years, systolic blood pressure under 100 mmHg, a GCS of less than 8, blood transfusion of more than ten units in the first 24 hours and colloid infusion of more than six litres in the first 24 hours. Multivariate analysis showed that age, T-RTS and ISS were independent determinants of mortality. A T-RTS of eight or less identified the cohort of patients at greatest risk (65%). The morphology of the fracture was not predictive of mortality. We recommend the use of the T-RTS in the acute situation in order to identify patients at high risk.

Does your board of trustees really know your hospital?

Hospital governing boards should be regularly and adequately informed of the important aspects of care rendered in their institutions. Such information must be provided in a concise and logical format that is easily understood by lay trustees and useful to their efforts to provide the most efficient, safest, and highest-quality care possible. This article offers a proposal for presenting quality information to hospital boards.

Effects of nitrous oxide exposure on behavioral changes in mice.

This study was designed to examine the effects of continuous exposure to low levels of nitrous oxide on several behavioral paradigms and the occipital cortex cells of mice. Different groups of mice were exposed to air or two different levels of nitrous oxide (1000 ppm or 2000 ppm) 8 hr/day for eight consecutive days. The exposure to nitrous oxide was achieved by placing animals in a specially designed, enclosed chamber. At the end of the exposure period, all mice were tested for motor coordination, locomotor activity, stereotypic behavior and anxiety level. Cellular examination of the occipital cortex was conducted by counting both the larger neural cells and the smaller neuroglial cells in a specific region. Our results indicated that animals showed no deficit in motor coordination or anxiety level. Histological examination indicated no significant difference in the number of neural cells, neuroglial cells, or total cells counted in the control tissue, as compared to the neural tissue from mice exposed to nitrous oxide. Nitrous oxide-exposed mice showed reduced locomotor activity compared to control animals; however, with the exception of one time period, this decrease was not statistically significant. Animals exposed to nitrous oxide showed a dose-dependent reduction in stereotypic behavior. Our results suggest that short-term exposure to trace levels of nitrous oxide might alter central dopaminergic neuronal activities in striatal and mesolimbic regions. Further research in this area is needed to provide more information regarding the potential effects of repeated exposure to low levels of nitrous oxide. (Pediatr Dent 15:93-98, 1993).

Cholinergic activation of the lobster cardiac ganglion.

The frequency of rhythmic burst activity of the isolated lobster cardiac ganglion is increased by exogenously applied acetylcholine and muscarinic agonists. Responses of individual motor neurons isolated from the ganglion by transection consist of a slow depolarization and repetitive bursting. The pharmacological profile of the receptors mediating this response is similar to that of vertebrate neuronal muscarinic receptors. Isolated ganglia incubated in the presence of [3H]-choline (18-19 h) exhibited radiolabelled acetylcholine accumulation. It is suggested that ganglionic excitation may be accomplished by extrinsic or intrinsic activation of muscarinic receptors on the motor neurons.

A radiographic investigation of third-molar development.

In view of limited investigations it was considered worthwhile to determine the impact of race, age, and gender on the development and calcification of third molars. Results showed that calcification of third molars could be estimated by observing one quadrant. The crown calcification process begins and is completed earlier in blacks. There were no significant gender differences.

Comparison of risk estimates using life-table methods.

Risk estimates promulgated by various radiation protection authorities in recent years have become increasingly more complex. Early "integral" estimates in the form of health effects per 0.01 person-Gy (per person-rad) or per 10(4) person-Gy (per 10(6) person-rad) have tended to be replaced by "differential" estimates which are age- and sex-dependent and specify both minimum induction (latency) and duration of risk expression (plateau) periods. These latter types of risk estimate must be used in conjunction with a life table in order to reduce them to integral form. In this paper, the life table has been used to effect a comparison of the organ and tissue risk estimates derived in several recent reports. In addition, a brief review of life-table methodology is presented and some features of the models used in deriving differential coefficients are discussed. While the great number of permutations possible with dose-response models, detailed risk estimates and proposed projection models precludes any unique result, the reduced integral coefficients are required to conform to the linear, absolute-risk model recommended for use with the integral risk estimates reviewed.

Dual effects of proctolin on the rhythmic burst activity of the cardiac ganglion.

The neuropeptide proctolin has distinguishable excitatory effects upon premotor cells and motorneurons of Homarus cardiac ganglion. Proctolin's excitation of the small, premotor, posterior cells is rapid in onset (5-10 s) and readily reversible (less than 3 min). Prolonged bursts in small cells often produce a "doublet" ganglionic burst mode via interactions with large motorneuron burst-generating driver potentials. In contrast to small cell response, proctolin's direct excitatory effects upon motorneuron are slow in onset (60-90 s to peak) and long-lasting (10-20 min). The latter include: a concentration-dependent (10(-9)-10(-7)M) depolarization of the somatic membrane potential; increases in burst frequency and enhancement of the rate of depolarization of the interburst pacemaker potential. Experiments on isolated large cells indicate: the slow depolarization is produced by a decrease in the resting GK and proctolin can produce or enhance motorneuron autorhythmicity . A two- tiered non-hierarchical network model is proposed. The differential pharmacodynamics exhibited by the two cell types accounts for the sequential modes of ganglionic burst activity produced by proctolin.

An assessment of health risk from radiation exposures.

A methodology has been developed to assess potential hazards from low-level exposures to radioactive pollutants. Estimates of dose rates to reference organs from internal and external exposure pathways (inhalation of contaminated air, ingestion of contaminated food or water, immersion in contaminated air, and exposure to contaminated ground surfaces) are computed with contemporary dosimetric models. These dose rates are used in a life-table analysis to estimate the radiation-induced cancer deaths and resultant years of life lost in an exposed cohort of 100,000 persons, all simultaneously liveborn and subject to the same risks of dying from competing causes (including natural background radiation). Estimates of the potential health risk are tabulated for approx. 150 radionuclides for each of the exposure pathways; results are summarized in terms of the probability of premature radiation-induced death for a member of the cohort due to incremental radiation exposure, and the average number of years of life lost per incremental fatality. The estimates of radiation-induced mortality generated by these methods provide a useful means of quantifying radiation risk; however, these estimates may be subject to large uncertainties, and can be best interpreted as a measure of the relative degree of hazard associated with exposures to various radionuclides through several exposure pathways.

Structure function analysis of an arthropod peptide hormone: proctolin and synthetic analogues compared on the cockroach hindgut receptor.

Proctolin is a pentapeptide (arg-tyr-leu-pro-thr) found in nervous tissues throughout the phylum Arthropoda. Initially described as a peptidergic neuromuscular transmitter, it now appears that proctolin is a major arthropod neurohormone modulating nervous activity, muscle tonus and contractile force. Structure-function studies with synthetic analogues demonstrate diverse peptides which retain agonistic activity, but few exhibit a high degree of affinity for the cockroach hindgut receptor compared with proctolin (Kdapp = 2 x 10(-8) M). High affinity agonists (Kdapp less than or equal to 10(-7) M) are limited to [phe2]-proctolin, [lys1]-proctolin and specific N-terminal additions. In this regard the hindgut receptor differs in its ligand specificity from that reported for the locust extensor tibia receptor. Using the analogue studies to predict sequences which may act as agonists, we have examined the known vertebrate peptide hormones for proctolin-like sequences. A possible relationship between vasoactive intestinal peptide, proctolin and erythrophore concentrating hormone is critically evaluated.

Some effects of proctolin on the cardiac ganglion of the Maine Lobster, Homarus americanus (Milne Edwards).

The neuropeptide proctolin has excitatory effects on the isolated lobster cardiac ganglion. Selective application to the anterior cell body region produces a dose-dependent (10(-8)--10(-5) M) prolonged depolarization of large anterior cells as well as marked increases in burst frequency and/or duration. In ganglia which have been silenced with tetrodotoxin, proctolin application to anterior cells elicits long-lasting depolarizing responses which are accompanied by a 10-30% increase of the apparent membrane input resistance. Higher proctolin concentrations produce high-frequency trains of driver potentials. It is proposed that a proctolin like peptide may serve a neurohumoral role in the lobster cardiac ganglion and that the anterior motor neurons exhibit endogenous rhythmicity in its presence.

The neuropeptide proctolin acts directly on Limulus cardiac muscle to increase the amplitude of contraction.

The pentapeptide proctolin increases the amplitude of contraction but not heart beat frequency of the isolated heart of Limulus polyphemus. It acts directly on the heart muscle and has no effects on the neurones of the cardiac ganglion or on the cardiac neuromuscular EJPs. A peptide with molecular weight, enzymatic susceptibilities and physiological effects similar to those of proctolin occurs in the Limulus cardiac ganglion. It is suggested that proctolin, or a family of proctolin-like peptides, may modulate muscle contraction in more than one subphylum of the Arthropoda.