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Biomedical subjects

R W Peters

Publications and source records attributed to R W Peters.

At least 145 records · Page 8Linked to original sources
PubMed1977

Auditory reaction times for functional and nonfunctional hearing loss.

Differences in decision processes as measured by auditory reaction times of simulated or actual functional hearing-loss subjects and nonfunctional subjects were investigated. Sensation level data are presented that reflect marked differences between such individuals with regard to probability of response, and means and standard deviations of auditory reaction times. Means and standard deviations of auditory reaction times for nonfunctional subjects are greatly reduced when compared with results obtained by simulated or actual functional subjects. Probability of response data was less effective in differentiating functional from nonfunctional subjects. Individuals who were trained to simulate hearing loss responded in a manner similar to functional patients. The results of this study suggest that auditory reaction time measures can be employed to determine the existence or nonexistence of functional hearing loss with considerable accuracy.

Audiometry↗
PubMed1977

Prognostic value of infranodal conduction time in patients with chronic bundle branch block.

His bundle recordings were obtained in 121 patients with chronic bundle branch block and the patients were followed for a mean period of 18 months. Seventy-nine patients had an infranodal conduction time (H-Q) less than 70 msec while 42 had H-Q greater than or equal to 70 msec. There was no significant difference in mean age, smoking history, diabetes, syncope, dizziness, blood pressure, and serum cholesterol or triglyceride levels between the two groups. There was a significantly greater incidence of progresssion to second degree or third degree atrioventricular block (9/42, 21%), and of severe congestive heart failure (16/42, 38%) in patients with H-Q greater than or equal to 70 compared with those with H-Q less than 70 (1/79, 1.3%; and 13/79, 16%, respectively). The risk of sudden death was significantly greater only in the group with H-Q greater than or equal to 70 and severe congestive heart failure. There was no correlation between the presence of first degree atrioventricular block and/or any particular type of bundle branch block pattern with sudden death and/or progression to second degree or third degree atrioventricular block. Analysis of the surface electrocardiogram is only of limited value in predicting high risk patients with chronic bundle branch block. Electrophysiologic studies are of greatest value in patients with bundle branch block with transient neurologic symptoms in whom no cause for the symptoms is evident.

Bundle-Branch Block↗
PubMed1976

The use of chicken tracheal organ cultures for the isolation and assay of avian infectious bronchitis virus.

A study has been made of the use of chicken tracheal organ cultures for the isolation and assay of avian infectious bronchitis (AIB) virus from both naturally and experimentally infected chickens. Six strains of AIB virus were investigated, 3 of which had been isolated from natural outbreaks of disease. Two of the virus isolations from the outbreaks of AIB were made directly into tracheal organ cultures without passage in embryonated eggs. Organ cultures prepared from 20-day-old embryos were used since they were found to be somewhat more sensitive in virus assay than those derived from chickens of up to 31 days of age. Ciliostasis, which was used as the marker of infectivity, was complete by 3 days after inoculation with each strain of virus examined. Virus could be isolated from both respiratory and non-respiratory tissue in tracheal organ cultures and these cultures were found to be at least as sensitive as 9-day-old embryonated eggs in detecting AIB virus either in pathological material or in serial dilutions. When virus was assayed in both systems, the titres were very similar. It is considered, therefore, that chicken embryo tracheal organ cultures offer a reliable alternative system to embryonated eggs for studying AIB virus.

Animals↗
PubMed1976

Atrial pacing in patients with sinus node dysfunction.

Sinus nod recovery time (SNRT) at paced atrial rates of 100 (SNRT100) and 120 (SNRT120) beats/min, atrial effective refractory periods at spontaneous heart rates (AERP) and at paced rates of 100 (AERP100) and 120 (AERP120) beats/min, and premature atrial stimulation were among the studies in evaluating 33 patients with symptomatic sinus node disease and 42 normal subjects. Although mean SNRT100 and SNRT120 were statistically significantly greater in patients than in control subjects, there was a significant overlap between patient and control groups, and SNRT100 or SNRT120 was associated with a 30.3 per cent false-negative and 5 per cent false-positive incidence. Correction for heart rate (SNRT-spontaneous cycle length) failed to improve the sensitivity or specificity of this test. There was no significant difference in mean AERP, AERP100 or AERP120, or in sinoatrial conduction time in patients compared with control subjects. Analyses of curves derived from plots of test and return cycles showed abnormal curves in only five of the 24 patients studied by progressively premature atrial stimulation. Two of these five patients showed normal zone I and II phenomena followed by a progressive linear increase in the return cycle that was thought to be due to abnormal refractoriness of the perinodal fibers.

Adult↗
PubMed1976

Precise "one line" measurement of intracardiac electrograms.

Atrioventricular nodal (A-H) and infranodal (H-Q) conduction times were determined in 22 patients undergoing intracardiac electrophysiologic studies. These measurements were determined independently both on line from a digital oscilloscope and from paper recordings at a rate of 100 mm/sec. There was no significant difference and excellent correlation between mean A-H (91.39 +/- 29 versus 95.44 +/- 32 msec) and H-Q (53.48 +/- 14 versus 50.52 +/- 15 msec) intervals determined by these two methods. The digital oscilloscope enables virtually instantaneous highly accurate (+/- 1 msec) timing of intracardiac events and rapid and more efficient processing of data. Potential applications during electrophysiologic studies include precise monitoring of drug effects on atrioventricular conduction and refractoriness, on line analyses of complex rhythm disturbances, and ready storage of data for computer retrieval and analyses.

Arrhythmias, Cardiac↗
PubMed1976

Growth kinetic studies of avian infectious bronchitis virus in tracheal organ cultures.

An egg-adapted vaccine strain (H120) and an organ culture-passaged field strain (HV-10) of avian infectious bronchitis (AIB) virus were propagated in tracheal organ cultures and their growth kinetics examined using nine-day-old embryonated fowl eggs and chick tracheal explants for virus assay. When the H120 strain was assayed in embryonated eggs, titres were approximately log10 2-0 ID50 (50 per cent infectious dose) per ml higher than when assays were performed in tracheal explants. The HV-10 strain, assayed in tracheal explants, yielded higher titres than did the H120 strain, but when assayed in embryonated eggs, yielded only minimal and variable virus titres.

Coronaviridae↗
PubMed1976

Organ culture studies on the efficiency of infection of chicken tissues with avian infectious bronchitis virus.

Long-term organ cultures of a range of tissues collected from specific pathogen-free chickens were employed to determine their susceptibility, and their capacity for subsequent virus production, following inoculation with avian infectious bronchitis (AIB) virus. When inoculated with approximately 2-0 log10 median ciliostatic doses (CD50) of a classical highly egg-adapted vaccine strain (H120) of AIB virus, 9 of 23 tissues were shown to be susceptible, namely the nasal turbinates, trachea, air sac membranes,lungsasal turbinates, trachea, air sac membranes, lungs, proventriculus mucosa, thyroid, kidney, ovary and oviduct. When the remaining 14 tissues were inoculated with a high dose of virus (6.8 log10 CD50), the conjunctiva, caecel tonsil, testis and bursa of Fabricius were susceptible whereas the oesophagus and cloaca responded minimally. Inoculation of the same range of tissues with a high or low dose of a field strain (HVI9) of AIB virus produced similar results, except for a number of individual variations in response, due possibly to strain differences in pathogenicity. Determinations of the minimal infectious dose requirements of the susceptible tissues revealed that the efficiency of infection with the H120 strain was highest for the nasal turbinate and tracheal tissues, and thereafter, in order of decreasing efficiency, were the air sac membranes, lung, oviduct, proventriculus mucosa, conjunctiva, kidney, ovary, bursa of Fabricius, thyroid, testis, caecal tonsil, cloaca and oesophagus. The relevance of these results is discussed in connection with the early events in the pathogenesis and the clinical syndrome of AIB infection in chickens.

Animals↗
PubMedDate not supplied

Coronary collateral blood flow in a patient with angiographically normal coronary arteries.

A 36-year-old man underwent coronary arteriography for evaluation of chest pain. His coronary arteries were smooth and free of obstructive disease. Selective right coronary injection revealed a large collateral vessel that opacified distal and proximal portions of the left circumflex coronary artery. Our case supports the view that coronary collateral vessels may occur in the absence of obstructive lesions.

Adult↗
PubMedDate not supplied

Pindolol therapy for bradycardia/tachycardia syndrome.

Bradycardia/tachycardia syndrome (BTS) is notoriously refractory to drug therapy. Three patients with BTS unresponsive to digitalis or digitalis plus verapamil (ventricular response continued intermittently rapid despite prolonged pauses) were prescribed oral pindolol, a beta blocker with intrinsic sympathomimetic activity. The ventricular rate was well-controlled in all and no adverse effects were seen. Pindolol may be of value in selected patients with BTS.

Aged↗