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Biomedical subjects

J D Road

Publications and source records attributed to J D Road.

46 records · Page 3Linked to original sources
PubMed1989

Granulomatous Pneumocystis carinii pneumonia mimicking tuberculosis.

A 62-year-old man with untreated, well-differentiated lymphocytic lymphoma, presenting with progressive dyspnea, was found on open lung biopsy to have multiple necrotizing granulomas that on frozen section were initially called tuberculosis. Routine Grocott methenamine-silver stain showed these to contain Pneumocystis carinii organisms. A review of the literature shows that this is an unusual histologic presentation that can occur in a wide variety of immunosuppressed states, including the acquired immunodeficiency syndrome. The histologic similarities to tuberculous infection are stressed to increase the awareness of possible misdiagnosis that could result in delayed or inappropriate therapy.

Diagnosis, Differential↗
PubMed1988

Effect of lung inflation on diaphragmatic shortening.

The effect of lung inflation on chest wall mechanics was studied in 11 vagotomized pentobarbital sodium-anesthetized dogs. Diaphragmatic shortening (percent change from initial length at functional residual capacity, %LFRC) and transdiaphragmatic pressure swings (delta Pdi) were compared with control values over a range of positive-pressure breathing that produced a maximum increase in lung volume to 40% of inspiratory capacity. There was no change in the electromyogram of the diaphragm or parasternal intercostals during positive-pressure breathing. delta Pdi and tidal volume (VT) fell to 52 +/- 3.3 and 42.5 +/- 5% (SE) of control. This was associated with a reduction in the initial resting length of 13 +/- 1.9 and 21 +/- 2.2%LFRC (SE) in the costal and crural diaphragms, respectively. Tidal diaphragmatic shortening, however, decreased to 66 +/- 7 and 57 +/- 7 and the mean velocity decreased to 78 +/- 10 and 63 +/- 8% (SE) of control for the costal and crural diaphragms, respectively. We conclude that the reduction in diaphragmatic shortening is the main determinant of the reduced delta Pdi and VT during lung inflation and relate this to what is currently known about diaphragmatic contractile properties.

Animals↗
PubMed1987

Measurement of signal period on a personal microcomputer and its application to the analysis of cardiac interval and blood pressure.

Personal microcomputers interfaced with analog-digital converters are capable of analyzing almost any biological signal, yet are limited in their ability to directly measure a signal's period/frequency. We describe a short program which measures the interval between periodic events up to 3.5 Hz. In addition, an expanded program which calculates the frequency distribution, distribution statistics, and cross regressions of cardiac interval and blood pressure is described.

Analog-Digital Conversion↗
PubMed1987

Ventilatory effects of stimulation of phrenic afferents.

The diaphragm, a ventilatory muscle, has abundant sensory innervation. The effects of phrenic afferent activation on ventilation have been varied. In this study the proximal end of the phrenic nerve was electrically stimulated, and the effects on ventilation were measured in supine dogs anesthetized with either alpha-chloralose or pentobarbital sodium. We found a maximum increase in ventilation of 45 +/- 4% in the alpha-chloralose group and an increase in mean arterial blood pressure of 18 +/- 4%. This response was obtained at high stimulus intensities (60 times twitch threshold). Stimulation of the proximal end of the gastrocnemius nerve produced a similar ventilatory response (61 +/- 10%) but at lower stimulus intensities. During pentobarbital sodium anesthesia both the hyperventilation and the pressor response were produced; however, ventilation was increased by an increase in respiratory frequency. The reflex was abolished by sectioning of the cervical dorsal roots (C4-C7). Proximal cold blockade of the nerve abolished the response at a perineural temperature of 1.35 +/- 0.64 degrees C. The main effect of activation of phrenic afferents was an increase in ventilation and blood pressure that was mediated by unmyelinated fibers and possibly thin myelinated fibers. This response is similar to skeletal muscle afferent activation and may play a role in ventilatory drive during such conditions as exercise and respiratory muscle fatigue.

Afferent Pathways↗
PubMed1987

Allergic angiitis of Churg and Strauss syndrome. Response to pulse methylprednisolone.

Our patient presented with widespread airspace consolidation. He was a steroid-dependent asthmatic receiving moderate doses of corticosteroid therapy. Open lung biopsy showed allergic angiitis of Churg and Strauss syndrome. The patient continued to deteriorate on high doses of prednisone. He was subsequently given four pulses of intravenous methylprednisolone with dramatic clearing noted on x-ray film and resolution of his shunt.

Adult↗
PubMed1986

Diaphragm length and breathing pattern changes during hypoxia and hypercapnia.

In this study diaphragmatic length changes were measured during quiet breathing and during augmentation of breathing with hypoxia and hypercapnia in supine anesthetized dogs. The breathing pattern and the VT-TI relationship during hypoxia were different than those during hypercapnia. The crural diaphragm shortened more than the costal diaphragm with both stimuli, and the amount of shortening in relation to the tidal volume implied that there was considerable distortion of the chest wall during hyperventilation. The velocity of shortening of both parts of the diaphragm at similar levels of ventilation was greater during hypoxia than hypercapnia. The velocities found with hyperventilation suggested that force-velocity considerations did not reduce force generation. Hypoxic stimulation resulted in a reduction in the resting length of both parts of the diaphragm, and was associated with a positive shift in baseline pleural pressure which implied gas trapping. The large tidal diaphragmatic shortening found with augmented breathing and the shorter resting length with hypoxia indicated that length-force properties are important in force generation.

Animals↗
PubMed1986

In vivo length and shortening of canine diaphragm with body postural change.

Using sonomicrometry, we measured the in vivo tidal shortening and velocity of shortening of the costal and crural segments of the diaphragm in the anesthetized dog in the supine, upright, tailup, prone, and lateral decubitus postures. When compared with the supine position, end-expiratory diaphragmatic length varied by less than 11% in all postures, except the upright. During spontaneous breathing, the tidal shortening and the velocity of shortening of the crural segment exceeded that of the costal segment in all postures except the upright and was maximal for both segments in the prone posture. We noted the phasic integrated electromyogram to increase as the end-expiratory length of the diaphragm shortened below and to decrease as the diaphragm lengthened above its optimal length. This study shows that the costal and crural segments have a different quantitative behavior with body posture and both segments show a compensation in neural drive to changes in resting length.

Animals↗
PubMed1985

Diffuse alveolar septal amyloidosis presenting with recurrent hemoptysis and medial dissection of pulmonary arteries.

An unusual case of recurrent hemoptysis in a 56-yr-old woman is presented. After all the usual investigations for hemoptysis, left lower lobectomy revealed medial dissection of small and medium-sized pulmonary arteries with evidence of amyloid deposition. The patient subsequently developed the clinical picture of diffuse alveolar septal amyloidosis in association with primary amyloidosis. Pulmonary artery dissection is briefly reviewed, and vascular amyloidosis is presented as the probable origin in this case.

Amyloidosis↗
PubMed1984

Diaphragm function and respiratory response after upper abdominal surgery in dogs.

Decreased diaphragm activity has been demonstrated after cholecystectomy in humans (Am. Rev. Respir. Dis. 127: 431-436, 1983). To investigate the mechanism(s) of postoperative diaphragm dysfunction we have established a dog model. Three groups of mongrel dogs were studied under general anesthesia: six dogs received no surgery (control); nine dogs underwent upper abdominal surgery (cholecystectomy); and six dogs underwent lower abdominal surgery (pseudoappendectomy). Diaphragm function was assessed by changes in transdiaphragmatic pressure swings, the ratio of changes in gastric to esophageal pressure swings, and the ratio of changes in abdominal to rib cage diameters during quiet tidal breathing. In the upper abdominal surgery group there were significant postoperative decreases in all parameters of diaphragm function and an increase in minute ventilation and respiratory frequency. However, there were no significant postoperative changes in the parameters of diaphragm function in the control or lower abdominal surgery groups. These studies establish that general anesthesia is not responsible for the reduced diaphragm activity seen postoperatively and that diaphragm function is not affected by lower abdominal surgery in dogs.

Abdomen↗