Biomedical subjects

J L Osborne

Publications and source records attributed to J L Osborne.

10 recordsLinked to original sources

PubMed1979

Ventilatory responses to carbon dioxide inhalation after vagotomy in chickens.

Both vagus nerves in 7 anesthetized chickens were cut midcervically. Inspired PCO2 was increased from 0 to 28 torr by successive 3.5 or 7 torr increments and then increased directly to 70 torr. At each level of PICO2, steady-state measures of PaCO2, [H+]a, VT, f and VE were made. When PICO2 was raised to 7 torr, PaCO2 AND [H+]a were above their control levels (i.e. PICO2 = 0); at each successive level of PICO2, both PaCO2 and [H+]a increased. Minute volume increased at 28 torr PICO2 but changes in VT and f individually were not significant. At 70 torr PICO2, VE and VT increased but f was not changed from its control value. We have previously suggested that CO2-sensitive intrapulmonary chemoreceptors mediate the arterial isocapnic hyperpnea at low PICO2 in chickens. The observation that vagotomy abolishes regulation of PaCO2 at low PICO2 is consistent with this hypothesis, since the afferent pathway of avian intrapulmonary chemoreceptors is predominantly vagal.

Animals↗

PubMed1978

Intrapulmonary and systemic CO2-chemoreceptor interaction in the control of avian respiration.

Experiments on anesthetized chickens were conducted to study interactions between afferent activity from the intrapulmonary and systemic CO2-sensitive chemoreceptors in the generation of respiratory amplitude (RA) and respiratory frequency (f). The thoracoabdominal cavity was opened, air sacs ruptured and each lung independently and unidirectionally ventilated. Intrapulmonary chemoreceptor activity was altered by changing the PCO2 of the ventilatory gas (PICO2) to the vascularly isolated right lung (VIL); systemic chemoreceptor activity was altered by changing the PICO2 to the denervated left gas exchange lung (GEL). Respiratory amplitude and frequency responses to changes in intrapulmonary PCO2 were determined at four levels of systemic arterial PCO2 (PaCO2). The results indicate that elevating PaCO2 shifts the pulmonary CO2-response curves for both RA and f to the left and increases the sensitivity of the RA-CO2 response curve but decreases the sensitivity of the f-CO2 response curve. We conclude that (1) interaction occurs between intrapulmonary and systemic afferent activity in the generation of RA and f, (2) the nature of the interaction is synergism with respect to RA and interference with respect to f, and (3) the interaction is greater during hypocapnia than hypercapnia.

Animals↗

PubMed1978

Avian intrapulmonary chemoreceptors: respiratory response to a step decrease in PCO2.

The contribution of intrapulmonary chemoreceptors (IPC) to the respiratory response, following a step decrease in PICO2 was assessed in anesthetized and unidirectionally ventilated chickens. Step changes in the PCO2 of the ventilatory gas (PICO2) to a single lung were introduced with PICO2 to the contralateral lung held constant. Respiratory amplitude and frequency were monitored. Experimental series were conducted under conditions such that (I) both systemic chemoreceptors and IPC, (II) systemic chemoreceptors alone and (III) IPC alone contribute to the ventilatory response. The results indicate (1) that a rapid component of the transient response (complete in 25 sec) is eliminated by sectioning the pulmonary nerves (Series II), and (2) within the rapid component, a localized minimum in respiratory amplitude was observed which was not seen in either Series II or Series III experiments. We conclude that the rapid component of the transient response is due to the CO2-sensitive IPC and that intrapulmonary and systemic chemoreceptors are not simply additive in the generation of respiratory amplitude and frequency, but a more complex interaction must be involved.

Animals↗

PubMed1978

Removal of intra-abdominal intrauterine contraceptive devices.

Thirteen cases of misplaced intrauterine contraceptive devices removed from the abdominal cavity over a two year period at the Chelsea Hospital for Women, are reviewed. Five of the six plastic devices were removable laparoscopically but all the copper containing devices required a laparotomy for removal because of an omental or peritoneal reaction.

Abdomen↗

PubMed1977

Ventilatory responses to CO2 in the chicken: intrapulmonary and systemic chemoreceptors.

The independent effects of pulmonary and arterial Pco2 on respiratory amplitude (RA) and respiratory frequency (f) were studied in unidirectionally ventilated chickens anesthetized with phenobarbital (160 mg-kg-1). Pulmonary Pco2 was set by the level of PIco2 ventilating the vascularly isolated right lung (VIL), whereas the systemic arterial Pco2 was set by the level of PIco2 ventilating the denervated left or gas exchange lung (GEL). The following results were obtained: 1) Increasing the PIco2 to the VIL from 0 to 35 torr and maintaining Paco2 constant at 2. torr increased RA from apnea to 76% of the animals' maximal hypercapnic response and decreased f: further increases in PIco2 to VIL had only minimal effects on RA and f. 2) increasing Paco2 from 19 to 61 torr and maintaining pulmonary Pco2 constant increased RA and decreased further increases in Paco2 had only slight effects on RA ulmonary chemoreflex and can dominate the control of RA during hypocapnic conditions, and (2) systemic CO2-sensitive chemoreceptors dominate the control of RA during hypercapnic conditions. It is suggested that the intrapulmonary chemoreceptors may act as a sensory system which plays a pertinent role in the regulation of parabronchial ventilation.

Animals↗

PubMed1977

Regulation of arterial PCO2 during inhalation of CO2 in chickens.

Since CO2-sensitive intrapulmonary chemoreceptors have been shown to exist in the avian lung, we conducted a series of experiments to determine if birds could regulate PaCO2 when confronted with an inspired CO2 load. Chickens were anesthetized with either pentobarbital (30 mg.kg-1) or phenobarbital (160 mg.kg-1). The PICO2 was either increased or decreased in successive 7 torr steps between 0 and 35 torr. At each level of PICO2, steady-state measurements of PaCO2, PaO2 and [H+]a were made. In three of ten experiments, tidal volume and respiratory frequency were determined and minute ventilation calculated. Our results indicate that as PICO2 is varied between 0 and 21 torr, minute ventilation increases and arterial homeostasis of PCO2 and [H+] is maintained; as the PICO2 is increased above 21 torr, PaCO2 increases. We conclude that the isocapnic hyperpnea associated with inhalation of CO2 in chickens is a CO2-coupled phenomenon and that it is mediated by CO2-sensitive intrapulmonary chemoreceptors.

Animals↗

PubMed1977

Dynamic responses of CO2-sensitive avian intrapulmonary chemoreceptors.

Single-unit extracellular potentials from CO2-sensitive intrapulmonary chemoreceptors (IPC) were recorded with tungsten microelectrodes from the nodose ganglia of unidirectionally, artificially ventilated White Leghorn cockerels. The responses of IPC to step and sinusoidal forcing functions of fractional concentration of carbon dioxide (FCo2) indicate that 1) about two-thirds of IPC are bidirectionally rate sensitive, 2) delay to forcing varies from essentially zero to several times larger than the time of nitrogen gas passage through the lung and, on the average, is significantly shorter to step decrease than step increase in fco2, and 3) IPC with irregular discharge intervals are more rate sensitive and respond to higher frequencies than IPC with regular interspike intervals. The physical and chemical properties of the "receptor-lung" complex are probably important in determining the dynamic responses of IPC by partitioning of CO2 from other gases within the lumen of the parabronchus. IPC are located along the length of the bronchial gas exchange areas of the avian lung and transmit information to the CNS concerning the mean level, rate, and direction of change in the partial pressure of carbon dioxide (PCo2).

Action Potentials↗

PubMed1976

The use of bromocriptine in the treatment of the unstable bladder.

Initial experience with the use of bromocriptine in 24 patients with troublesome micturition symptoms associated with an unstable bladder is described. 14 patients responded symptomatically to treatment with bromocriptine and these results were confirmed by a double blind trial in this group. 11 of these patients had previously failed to benefit from treatment either with drugs or vesical distension. It is concluded that bromocriptine has a part to play in the treatment of some cases of primary detrusor instability.

Adolescent↗

PubMed1975

A urodynamic view of bladder outflow obstruction in the female: factors influencing the results of treatment.

169 female patients with outlet obstruction have been studied urodynamically. The results of treatment of the outlet obstruction in 102 patients have been analysed and the reason for the failures discussed. Patients with stable detrusors and those with symptoms of recurrent urinary tract infection responded well to treatment, provided this relieved the obstruction adequately; symptomatic relief was less common in patients with unstable detrusors, despite adequate outflow readjustment.

Adolescent↗

PubMed1975

A urodynamic analysis of micturition symptoms in the female.

The presenting symptoms of 570 females with micturition disorders have been studied with particular reference to the urodynamic state of the detrusor in an attempt to define those symptoms and symptom complexes which are associated with the presence of absence of detrusor instability. The results show that patients who complain of recurrent urinary tract infection or stress incontinence in the absence of any other micturition symptoms usually have stable bladders and do not require cystometric confirmation of this fact. When the symptom of urge incontinence is associated with persistent frequency and nocturia, there is a high correlation with detrusor instability, although hypersensitive urethral states which may present with identical symptoms and are usually associated with stable bladders are difficult to differentiate clinically. Groups of patients in whom it was difficult to predict the detrusor state from the symptoms were studied, and the results of a prospective analysis, predicting the detrusor state from the micturition history of 230 incontinent females, have been presented.

Cystitis↗