PubMed Health⌕ Search

Biomedical subjects

D H Carr

Publications and source records attributed to D H Carr.

At least 19 recordsLinked to original sources
PubMed1992

Role of right heart receptors in the control of renin, vasopressin, and cortisol secretion in dogs.

We have reported that increased left heart pressure inhibits increases in plasma renin activity (PRA), arginine vasopressin (AVP), and cortisol during arterial hypotension. The goal of this study was to determine whether increases in right heart pressure also inhibited hormonal responses to hypotension. Seven dogs were chronically instrumented with inflatable cuffs around the ascending aorta (AA), the pulmonary artery (PA), and the thoracic inferior vena cava (IVC), as well as with catheters in both atria, the abdominal aorta, and vena cava. The IVC, the PA, and the AA cuffs were inflated on different days to cause step reductions in mean arterial pressure (MAP) of 5, 10, 20, and 30% below control MAP. Graded constriction of the AA caused large increases in left atrial pressure and plasma atrial natriuretic peptide (ANP), but had no effect on plasma AVP or cortisol and caused only a small increase in PRA at the maximal reduction of MAP. Constriction of the IVC reduced both atrial pressures and plasma ANP, but stimulated increases in PRA, AVP, and cortisol. Constriction of the PA increased right atrial pressure and plasma ANP and caused increases in plasma AVP and cortisol that were similar to responses during IVC constriction, but the PRA response was only half (P < 0.05). These results indicate that increasing pressure on the right side of the heart can attenuate the PRA response to hypotension, and suggest that the inhibition is mediated by the rise in plasma ANP.

Animals↗
PubMed1991

Advanced multiple beam equalization radiography (AMBER) in the detection of diffuse lung disease.

To evaluate the effects of scanning equalization radiography (SER) on the detection of diffuse lung disease a clinical comparison between an Advanced Multiple Beam Equalization Radiography (AMBER) unit and conventional chest radiography was performed. Even though the overall detection of focal pulmonary lesions with the AMBER unit has been shown to be significantly higher than with conventional radiography because of the improved demonstration of the costophrenic and retrocardiac regions, the utility of AMBER in the demonstration of diffuse lung disease has not been established. Twenty-one patients with diffuse lung disease (fibrosing alveolitis or sarcoidosis) and six patients with no pulmonary disease had high kVp frontal and lateral chest radiographs on both an AMBER unit and a conventional chest stand. The pooled results of five observers using Receiver Operating Characteristic (ROC) analysis indicate that there is a slight improvement but no statistically significant difference in observer performance between AMBER (Area under the ROC curve AZ = 0.934) and conventional radiography (AZ = 0.868) in the task of detecting diffuse lung disease.

Evaluation Studies as Topic↗
PubMed1991

Some physiological and pharmacological factors affecting uterine motility as measured by electromyography in the mare.

Two intact and 2 ovariectomized mares aged 3-16 years had bipolar electrodes implanted in the myometrium to measure electromyographic (emg) activity during normal and exogenously simulated (with oestrogen and progesterone) cyclical activity (anoestrus, transition, oestrus and dioestrus). Oxytocin, cloprostenol, propantheline bromide and clenbuterol were administered during each cycle stage. In 1 mare, emg activity was recorded during natural breeding (4 times) and through the first 20 days of pregnancy. Simultaneous intrauterine pressure recordings (IUP) using an open tipped catheter system were taken occasionally. For mares in oestrus, we recorded short bursts of high amplitude emg activity separated by quiet periods, a pattern that is indicative of uterine contractions. During dioestrus the duration of emg activity increased, but amplitude decreased and interspersed quiet periods were less well defined, indicative of uterine tonus. The emg patterns seen in anoestrus and transition were intermediate. At breeding there was a short-lived increase in emg activity, unlikely to be caused by endogenous hormone release. During early pregnancy the emg characteristics varied depending on whether the fertilized ovum was in the oviduct, migratory or fixed, with emg activity increasing to 100% after Day 16 when uterine tone is maximal. Oxytocin and cloprostenol caused prolonged emg activity followed initially by a short burst pattern that was most pronounced in oestrus and least in dioestrus and suggests uterine motility is stimulated to a greater extent during oestrus. Propantheline decreased emg activity, whereas cloprostenol caused minimal changes. IUP increased with uterine stimulants and decreased with uterine relaxants, but showed little variation between cyclic states. There was little correlation, statistically or visually, between IUP and emg activity during the oestrous cycle with or without drug treatment. Because emg analysis gave consistent results and demonstrated significant differences between oestrus and dioestrus that neither agreed nor correlated with IUP, the validity of the IUP recording technique used in this study (as well as those used in general for the mare) is questioned. It is suggested that extrauterine factors such as intestinal motility and intra-abdominal pressure changes could influence IUP responses.

Animals↗
PubMed1990

Computed tomography of folded lung.

Computed tomography (CT) scans of 22 examples of folded lung in nine patients were reviewed. The most important CT criteria of folded lung are the presence of vessels and bronchi running in a smooth curvilinear fashion towards a peripheral mass with an ill defined central edge associated with pleural thickening. These features were seen in all 22 examples. The lesions are frequently multiple (eight out of nine patients). When these features are present the diagnosis can be made without recourse to biopsy or thoracotomy. Enhancement with intravenous contrast medium is unnecessary and does not provide any extra useful information. Various other previously described criteria such as air bronchograms are not necessary for the diagnosis.

Humans↗
PubMed1990

Abnormal regional distribution of ventilation in middle-aged smokers: comparison of changes in 81Krm ventilation scans and computed tomography of the lung.

In 1980 we found that abnormalities in regional distribution of ventilation, as assessed by 81Krm lung scans, were common in middle-aged smokers with normal chest radiographs and mild impairment of overall lung function. In 1984 we repeated 81Krm scans in 16 continuing smokers then aged 50-64 years and with mean forced expiratory volume in one second 93% (20 SD) of predicted values who had previous 81Krm scans performed in 1980. To assess the role of disease of the peripheral airspaces in causing abnormal regional ventilation, we also obtained computed tomograms (CT) of the lungs and measured carbon monoxide transfer of the lungs in these men. Krypton scans in seven men who had normal or minor focal defects of ventilation in 1980 were unchanged in 1984. Scans in seven of the nine men who had abnormal scans in 1980 remained abnormal in 1984 but there was no overall deterioration in the abnormality of ventilation in these men; in men with similar grading in 1980 and 1984 some of the peripheral defects present in 1980 had resolved and some new abnormal areas had appeared. Minor localised abnormalities of CT scans, as assessed visually, were present in eight of the 16 men and were associated with lower values of carbon monoxide transfer coefficient (mean 78% vs 98% predicted in men with normal scans, P less than 0.01) and lung density (mean -894 vs -869 HU in men with normal scans, P less than 0.054) suggesting the CT changes were due to alveolar destruction. Abnormality of the krypton scan was not significantly associated with abnormality of the CT scan or with a reduction in carbon monoxide transfer. The results of the krypton lung scans confirm that non-uniformity of regional ventilation is often present in asymptomatic middle-aged smokers and suggest that this non-uniformity is in part due to temporary occlusion of airways. Abnormality in regional ventilation was not associated with the anatomical changes shown by the CT scan, suggesting that airway narrowing was more important than alveolar destruction in causing regional abnormalities of ventilation in these men.

Forced Expiratory Volume↗
PubMed1989

Computed tomography appearances of pulmonary alveolar proteinosis.

The computed tomography appearances of six patients with pulmonary alveolar proteinosis are reported. In all patients the appearances are similar and are unlike pulmonary opacities in any other disease; in one patient they suggested the diagnosis. The CT appearances correlate well with histology and demonstrate septal thickening within lung involved by the disease.

Adult↗
PubMed1979

Parental origin of triploidy and D and G trisomy in spontaneous abortions.

A cytogenetic study of 15 triploid spontaneous abortuses, 12 trisomic abortuses, and their parents was carried out using the Q-banding technique. Polymorphic regions in abortus chromosomes were compared to corresponding regions of parental chromosomes to determine the origin of the extra chromosomes. Using marker chromosomes it was found that 7 triploids and only one trisomy were informative. Three triploids arose by failure to shed the second polar body during oogenesis. One triploid arose by dispermy. The other three triploids inherited an extra haploid set of chromosomes from the father, either by dispermy or by failure of the second meiotic division during spermatogenesis. The only informative trisomy, a trisomy 22, inherited the extra 22 from the mother. Chromosome polymorphisms are useful in determining the parental origin of extra chromosomes in certain cases.

Abortion, Spontaneous↗
PubMed1979

Trophoblast growth in the lungs of mice.

Trophoblast giant cells grow from ectoplacental cones of 7 1/2 days' gestation that are implanted in the lung from the surface, intrabronchially, or via the circulation. When blastocysts of 3 1/2 days' gestation are implanted in lung, their behavior varies according to the route of implantation and the ages of the recipient mice. Blastocysts produced trophoblast giant cells when implanted in the bronchial tree. Trophoblast giant cells were not seen in adult lungs when blastocysts were introduced via the circulation. However, they were seen in 12-day-old mice injected in the same way 10 days previously. Something is apparently liberated from adult lung vessels which interacts with the blastocyst or zona pellucida and causes rapid degeneration of trophoblast. Experiments designed to extract this agent are in progress in the hope that the agent may be useful in the treatment of human trophoblastic disease.

Animals↗
PubMed1978

Vagally induced gastric antral contractions and gastric emptying of a liquid test meal.

The emptying of a liquid test meal from the stomach was studied during, and in the absence of, electrical stimulation of cut ends of a thoracic branch of the vagus in anaesthetized cats. The test meal (154 mmol.1-1 NaCl and 30 mg.1-1 phenol red) was measured by collecting effluent from a duodenal fistula over a 30 min period. The stomach emptied about 60% of the meal under control conditions compared with over 90% during efferent stimulation of the vagus. The increased volumes emptied during efferent stimulation were not accounted for by secretion of gastric acid. Coincident with the vagally evoked antral contractions there was a gush of liquid from the duodenal cannula. Afferent vagal stimulation resulted in an initial marked delay of emptying followed by an acceleration so that the volume emptied after 30 min was similar to that in control experiments. Antral contractions, evoked by efferent vagal stimulation, accelerated the emptying of a liquid test meal from the stomach.

Animals↗
PubMed1978

Q-banding of chromosomes in human spontaneous abortions.

Chromosome studies of 242 spontaneous abortions were carried out by Q-banding technique. The abortuses were selected for study because they were phenotypically abnormal, had not progressed beyond 12 weeks development or were from women with repeated abortions. Chromosome anomalies were found in 126 (52%) of the abortuses. Of these, 71 (56%) were trisomies. Trisomies were found for all the autosomes except Nos. 1, 3, 5, 11, 17 and 18. Triploidy was the second commonest anomaly in this series, making up 26 (21%) of the total anomalies. About 70% of these had an XXY sex chromosome complement. Only 16 (13%) of the abortuses had X monosomy, a lower frequency than would be expected in an unselected study. Tetraploidy was found in 8 abortuses and the 5 remaining specimens had various anomalies. These included 3 translocations, a trisomy 21,X monosomy and a ring chromosome 13. Except for the greater frequency of XXY than XXX sex chromosomes in the triploids, there was no evidence of a distortion of the sex ratio, either among the trisomic or among the chromosomally normal abortuses.

Abortion, Spontaneous↗
PubMed1977

An experimental study of trophoblast growth in the lung.

Trophoblast can be grown from blastocysts or ectoplacental cones of the mouse in a variety of extrauterine sites. An attempt was made to grow trophoblast in the lung under various conditions. In 94 mice, blastocysts, or cones, were introduced into the lung through the vascular system. Trophoblast growth never occurred. However, when blastocysts, or cones, were introduced directly into the lung, trophoblast grew in 30-50% of mice, depending on technique. Failure to grow from the intravascular position does not appear to be due to liberation of common products of ischemia because blastocysts produced normal trophoblast in the liver when implanted via the portal system, even in the presence of extensive necrosis. The inhibiting factor, which is apparently produced in the lung, is being investigated.

Animals↗
PubMed1976

Four familial translocations ascertained through spontaneous abortions.

In a study of 514 spontaneous abortions, 194 were found to have a chromosome anomaly. Of these, 4 (2.1%) were unbalanced translocations. Three of the translocations were Robertsonian (13q14q) and one was reciprocal. Each translocation was ascertained independently and each was associated with a balanced rearrangement in a carrier parent.

Abortion, Spontaneous↗
PubMed1975

Recent advances in the cytogenetic study of human spontaneous abortions.

A cytogenetic study of 27 spontaneous abortions was carried out using the Q-banding technic. The specimens were selected for study in order to increase the likelihood of finding a chromosome anomaly. Sixteen of 27 specimens (59%) showed a chromosome abnormality. Trisomy was found in 9 of the specimens, and the chromosomes involved were Nos. 2, 8, 14, 16, and 22. There were 5 triploids and 2 tetraploids. Using marker chromosomes, it was found that the extra haploid set was paternally derived in two of the triploids which were favorable for study. The Q-banding technic provides accurate identification of the extra chromosomes in trisomy. When favorable markers are present in the parents, the source of the extra haploid set can be identified in triploid abortuses.

Abortion, Spontaneous↗