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P R Sheehe

Publications and source records attributed to P R Sheehe.

At least 37 records · Page 2Linked to original sources
PubMed1987

A quantitative analysis of sniffing strategies in rats performing odor detection tasks.

The sniffing strategies of rats performing two learned odor detection tasks were monitored with a pneumotachograph and quantitatively analyzed with respect to fifty-two characteristics. The results of this study demonstrated that the rat's sniffing varied for different odorants, different concentrations of the same odorant, and between air and odor trials. The variations resulted from changes in such descriptors as volume, duration, average flow rate, peak flow rate and sniff number. In general, a sniffing pattern began with one or two inspirations followed by alternating inspirations and expirations. Comparison of earlier and later sniffs in a bout demonstrated a growth towards both a maximum inspiratory and expiratory sniff which had the largest duration, volume, average flow rate and peak flow rate. These maximum sniffs occurred at or near the end of a bout. Although analysis of the fifty-two characteristics was quantitatively useful in determining the physiologic values and airflow patterns generated by sniffing, a single univariate response measure incorporating twelve characteristics was the best descriptor of how sniffing patterns varied with odorant stimuli.

Animals↗
PubMed1987

"Imposed" and "inherent" mucosal activity patterns. Their composite representation of olfactory stimuli.

Both regional differences in mucosal sensitivity and a gas chromatography-like process along the mucosal sheet have been separately proposed in two sets of earlier studies to produce different odorant-dependent activity patterns across the olfactory mucosa. This investigation evaluated, in one study, whether and to what degree these two mechanisms contribute to the generation of these activity patterns. Summated multiunit discharges were simultaneously recorded from lateral (LN) and medial (MN) sites on the bullfrog's olfactory nerve to sample the mucosal activity occurring near the internal and external nares, respectively. Precisely controlled sniffs of four odorants (benzaldehyde, butanol, geraniol, and octane) were drawn through the frog's olfactory sac in both the forward (H1) and reverse (H2) hale directions. By combining the four resulting measurements, LNH1, LNH2, MNH1, and MNH2, in different mathematical expressions, indexes reflecting the relative effects of the chromatographic process, regional sensitivity, and hale direction could be calculated. Most importantly, the chromatographic process and the regional sensitivity differences both contributed significantly to the mucosal activity patterns. However, their relative roles varied markedly among the four odorants, ranging from complete dominance by either one to substantial contributions from each. In general, the more strongly an odorant was sorbed by the mucosa, the greater was the relative effect of the chromatographic process; the weaker the sorption, the greater the relative effect of regional sensitivity. Similarly, the greater an odorant's sorption, the greater was the effect of hale direction. Other stimulus variables (sniff volume, sniff duration, and the number of molecules within the sniff) had marked effects upon the overall size of the response. For strongly sorbed odorants, the effect of increasing volume was positive; for a weakly sorbed odorant, it was negative. The reverse may be true for duration. In contrast, the effect of increasing the number of molecules was uniformly positive for all four odorants. However, there was little evidence that these other stimulus variables had a major influence upon the effects of the chromatographic process and regional sensitivity differences in their generation of mucosal activity patterns.

Acyclic Monoterpenes↗
PubMed1987

Improvement of olfaction in laryngectomized patients with the larynx bypass.

Hyposmia following laryngectomy is an often recognized phenomenon. A larynx bypass device was used to determine whether this olfactory deficit could be reversed simply by restoring nasal airflow. Odorant detection thresholds and confusion matrix identification tests were administered to laryngectomy and normal comparison groups. Data on nasal airflow characteristics with and without the bypass were also analyzed. The results suggested that restoration of nasal airflow completely reversed the hyposmia for trigeminal nerve stimuli. However, the reversal of hyposmia was not complete for those odorants which primarily, if not exclusively, stimulate the olfactory nerve. This suggested that other factors may contribute to laryngectomy-induced hyposmia for olfatory nerve stimuli. Additionally, nasal airflow analysis revealed that confusion matrix identification scores were depedent upon inspiratory sniff flow rates with and without the larynx bypass. It is argued that rehabilitation for the laryngectomee should include efforts to restore and maintain preoperative olfactory acuity.

Adult↗
PubMed1984

A parametric study of the stimulation variables affecting the magnitude of the olfactory nerve response.

The magnitude of olfactory responses can be related to three primary variables [number of odorant molecules (N), sniff volume (V), and sniff duration (T)] and three derived variables [concentration (C = N/V), flow rate (F = V/T), and delivery rate (D = N/T)]. To evaluate the effects of these interdependent variables upon the olfactory response, the summated multiunit discharges were recorded from the olfactory nerves of nine frogs in response to octane presented at two levels (in 2:1 ratio) of each primary variable. This presentation defined eight "sniff" combinations representing three levels of each derived variable. In an ANOVA of the logs of the responses, the effect of each primary variable was highly significant, with no significant interactions. A multiplicative regression model incorporating the effects of the three primary variables represented responses exceedingly well, with positive effects of N and T and a negative effect of V. When, with this model, the effect of each of the derived variables was isolated from the effects of all other variables, the analysis showed a positive effect for C, a near-zero positive effect for D, and a negative effect for F. Placing certain constraints upon the model parameters generates 13 distinct one- and two-variable models (e.g., the [C, T] model requires N and V to have equal but opposite effects). In ranking these reduced models in terms of their ability to predict the neural response, the predictive ability of [F, N] and [C, T] was at least as good as that of the three-variable model.

Analysis of Variance↗
PubMed1983

A variable risk clinical prognostic compartmental model.

A model for predicting the occurrence of disease endpoints from a knowledge of baseline variables and intermediate events is described and illustrated with numerical examples. Maximum likelihood equations are developed and maximum likelihood estimates of coefficients in risk functions of variables included in a stepwise upward procedure are applied to a small set of data for illustrative purposes.

Adult↗
PubMed1982

Improved electrocardiographic criteria for the diagnosis of inferior myocardial infarction.

New electrocardiographic (ECG) criteria for the diagnosis of inferior myocardial infarction (IMI) are proposed. The criteria are based upon the relationships between portions of the vectorcardiographic (VCG) QRS loop in the frontal plane and the corresponding portions of the ECG QRS complexes recorded in leads II and III. The application of the proposed criteria requires that the tracings be obtained with three-channel ECG machines so that the temporal relationships between the QRS complexes in lead II and those in simultaneously recorded lead III can be inspected. This type of analysis of the ECG permits important features of the contour of the VCG QRS loop to be predicted. The proposed ECG criteria for the diagnosis of IMI are: in the absence of counterclockwise rotation in the frontal plane, (1) Q waves of 30 msec or longer in lead II or (2) regression of initial inferior forces from lead III to lead II. The proposed ECG criteria were evaluated in an initial series of 333 patients and, using a blind experimental design, in a confirmatory series of 94 patients. The performance of the proposed criteria was statistically superior to that of two sets of ECG Q-wave criteria and comparable to that of the VCG criteria of Starr et al.

Adult↗
PubMed1979

A prognostic model for head injury.

A prognostic model for head injured patients was developed. Patients fall into one of four prognostic categories at the end of the first hospital day: I. Discharge alive on or before the seventh hospital day. II. Discharge alive 8--42 days after admission. III. Discharge alive after 42 days, or dead after five years. IV. Discharge dead before five years. The outcome of 63% of the patients was predicted correctly. The model correctly placed, or missed by only one category, 97% of the patients observed. Errors tended to the optimistic side of observed outcomes. Age and pattern of consciousness were critical prognostic factors.

Adolescent↗
PubMed1979

On the epidemiology of human toxoplasmosis in Scandinavia especially in children.

A random sample representing approx. one-third of pre-school children and approx. 95% of school children in age groups 8, 11, 13, and 15 years in a suburb of Stockholm were examined for antibodies to Toxoplasma. Antibodies were uncommon in small children. They gradually appeared throughout childhood but especially in adolescence and adult life. Antibodies were more common in females than in males. Even small girls were more often infected than boys of corresponding age. The difference becomes marked in puberty and is significant in adults. A family study revealed evidence of familial aggregation of the infection albeit with borderline significance. No correlation was found between occurrence of antibodies and the presence of cats in the families or reported consumption of raw meat. The majority of representative samples of Lapps and Skolt Lapps in northern Scandinavia lacked antibodies to Toxoplasma.

Adolescent↗
PubMed1979

Neonatal respiratory instability and infant development.

This study examines the relationships between neonatal sleep respiratory instability and infant development. A group of 122 full-term healthy infants was observed during a nap within the first and fourth weeks of life. During each nap, a continuous polygraphic recording was obtained of respiratory activity and extraocular movements. The relative frequency and average duration of apneic pauses (greater than or equal to 2 sec) in each testing session for an infant were employed to calculate a measure of respiratory instability (PSA4) previously found to be related to the occurrence of prolonged sleep apnea. 28 of the infants in this study were maintained at home on apnea monitors. The Bayley Scales of Infant Development were administered to each infant at approximately 9 months of age. Comparisons of infants with high versus low PSA4 values and of monitored versus unmonitored infants were not strongly distorted by imbalances in birth weight, sex, race, birth order, method of feeding, Sudden Infant Death Syndrome (SIDS) sibship, parental education, age at developmental assessment, and developmental tester. Those with increased respiratory instability (PSA4 greater than or equal to -0.04) within the first week of life averaged significantly lower in mental and psychomotor development. Utilization of home apnea monitors was not significantly associated with developmental scores.

Child Development↗
PubMed1977

Terminology.

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HLA Antigens↗