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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↗
PubMed1988

Ultrasound, CT, and MRI comparison in primary and secondary tumors of the liver.

Thirty-five patients with surgically removed or percutaneous biopsy-proven tumors were examined by ultrasound, computed tomography (CT), and magnetic resonance imaging (MRI). This retrospective study describes the appearance of the primary tumors and metastases and compares the sensitivity and specificity of the 3 imaging methods. Ultrasound, CT, and MRI examinations as well as clinical, operative, and/or histologic data were available for all 35 patients. Paramagnetic contrast agent gadolinium-diethylenetriamine pentaacetic acid (Gd-DTPA) was used in 23 patients and a short TI inversion recovery MRI sequence was used in 23 patients, in addition to various spin echo MRI sequences. Thirteen patients were examined using both Gd-DTPA and the short TI inversion recovery sequence. Our comparative study--based on the following criteria: detection, size, location of the tumor, and portal vein involvement and bile duct dilatation--demonstrated an advantage of MRI over ultrasound in 16 of 35 cases, equal results in 17 of 35 cases and a disadvantage of MRI compared to ultrasound in 2 of 35 cases. With the identical criteria, MRI proved to be more informative than CT in 10 of 35 cases, equal in 21 of 35 cases, and less informative in 4 of 35 cases.

Adolescent↗
PubMed1987

Effective long-term treatment of acromegaly with a long-acting somatostatin analogue (SMS 201-995).

Nine acromegalic patients, six previously untreated, were studied before and after 3-15 months of treatment with a long-acting somatostatin analogue (SMS 201-995; 100 micrograms injected s.c. three times daily). During treatment, the mean (+/- SEM) 24-h GH concentration fell from 82 +/- 22 mIU/l to 33 +/- 7 mIU/l (P less than 0.001), and eight of the 9 patients showed a reduction of at least 50% in GH levels in the fasting state and/or during a glucose tolerance test. There was a significant 30% fall in serum concentrations of insulin-like growth factor (IGF-1) with SMS. All patients showed rapid clinical improvement, with diminished sweating and headaches, and reduction in skinfold thickness, hand volumes and finger size. Computer tomographic scanning of the pituitary in eight patients showed no change in the size of the pituitary tumour during treatment. The only side-effects of SMS noted were transient abdominal discomfort and loose stools in two patients on initiating therapy. Although fasting plasma glucose concentration did not change during treatment (5.4 +/- 0.3 vs 5.5 +/- 0.3 mmol/l), mean 24-h plasma glucose concentration was higher with SMS (6.6 +/- 0.5 mmol/l vs 6.0 +/- 0.4 mmol/l; P less than 0.02). Mean 24-h plasma insulin concentration fell from 87 +/- 11 mIU/l before treatment to 39 +/- 6 mIU/l during treatment (P less than 0.005). No change in other anterior pituitary hormones was observed. SMS appears to be a safe, rapidly effective, long-term treatment for certain patients with acromegaly.

Acromegaly↗
PubMed1987

Long term follow-up of patients with Cushing's disease treated by interstitial irradiation.

The first 86 patients with Cushing's disease treated with interstitial irradiation (by needle implantation) as the sole therapy were reviewed. In the 82 patients who were reassessed 1 yr after treatment 63 (77%) achieved remission. This study comprises the outcome and complications in the 54 patients who had a remission and whom we were able to follow. The follow-up period ranged from 3-26 yr (mean, 10.5) from the time of remission. No instance of clinical or radiological relapse has occurred. Of these 54 patients, yttrium-90 alone was used in 32, of whom 12 (37%) required corticosteroid or T4 replacement therapy in a mean time of 3.5 months; in 7 of these 12 we elected to give an ablative dose. Gold-198 alone was used in 15 patients, of whom 7 (47%) developed hypopituitarism in a mean time of 76 months. Both isotopes were used in 7 patients. A diurnal serum cortisol rhythm was found in 28 of the 31 patients who were not receiving corticosteroid therapy. In 5 of the 7 patients with an initially abnormal pituitary fossa, serial radiological studies revealed remodelling in 3. There have been no complications in the last 17 years. Pituitary implantation with yttrium-90 is an effective alternative to transsphenoidal hypophysectomy, with a high remission rate, no recurrence (as yet), no operative complications, and avoidance of hormone replacement in the majority.

Adolescent↗
PubMed1987

The afferent innervation of the face of sheep and goats.

The sensory innervation of the maxillary hairy skin and buccal mucous membrane was studied in anaesthetised sheep and goats. An electrophysiological technique isolated 47 single afferent units from the infraorbital nerve under chloralose or halothane anaesthesia. Mechanoreceptors of hairy skin were located in association with the following features: sinus hairs (n = 9); central primary hairs (n = 18); clear marginal hairs (n = 7) and skin-not-hair (n = 3). Units responded to hair tip displacement of 35 to 50 microm. Afferent units were also located in the mucous membrane of the cheek either associated with conical papillae (n = 8), or unassociated with papillae (n = 1). Receptor responses associated with hairs were classified as rapidly adapting (n = 18) and slowly adapting (n = 18) mechanoreceptor responses during sustained hair deflection. Seven mechanoreceptors of hairy skin and mucous membrane were excited by a fall in surface temperature. Two specific cold thermoreceptors were found: one in hairy skin and one in the mucous membrane. These units had phasic discharges during abrupt thermal depression and static discharges at constant surface temperatures. All afferent units had myelinated axons as indicated by their conduction velocities (range 20 to 57 m sec-1, mean 34 m sec-1). It is concluded that the mechanoreceptors identified had similarities with those of other mammalian species and some distinct differences. An interesting feature of mechanoreceptors in the buccal mucosa was their cold sensitivity. They therefore shared characteristics with mechanoreceptors in the penile mucosa of the ram and tongue of the sheep.

Animals↗
PubMed1987

Neurophysiologic maps of cutaneous innervation of the external genitalia of the ram.

The area of skin innervated by the afferent fibers in a peripheral nerve is called the cutaneous area (CA) of that nerve. Mapping of those areas that were responsive to movement of wool/hairs in the genital region of 18 anesthetized rams, combined with subsequent identification of spinal nerves and dissection of the pudendal nerve plexus, indicated considerable differences in the extent of the CA and the origins of cutaneous branches from the pudendal plexus. The CA of the proximal and distal cutaneous branches of the pudendal nerve (or plexus) overlapped craniocaudally by approximately one-half, and the latter included most of the skin of the ipsilateral half of the scrotum. The CA of the deep perineal and caudal rectal nerves lay immediately adjacent to the anus. The CA of the scrotal branches of the pudendal nerve were restricted primarily to the scrotum. Fascicles in the dorsal nerve of the penis irregularly supplied CA along the length of the prepuce and consistently supplied the cranial free end of the prepuce. The CA of the ventral cutaneous branches of the caudal thoracic spinal nerves, the first 2 or 3 lumbar spinal nerves, and the genitofemoral nerve extended to the midline of the prepuce. Overlapping of CA was extensive, especially on the prepuce.

Animals↗
PubMed1986

Remission of symptoms during long term treatment of metastatic pancreatic endocrine tumours with long acting somatostatin analogue.

Five patients with metastatic pancreatic endocrine tumours injected a long acting somatostatin analogue (SMS 201-995) 50 micrograms subcutaneously every 12 hours and were followed up for three to six months. Treatment aimed at controlling excess secretion of hormone by the tumours thereby bringing symptomatic relief. Four patients showed a significant reduction in tumour related hormone concentrations but in none did values return to normal. All five patients, however, noted definite symptomatic improvement and in one this was dramatic (disappearance of life threatening diarrhoea and correction of metabolic acidosis and hypokalaemia within 48 hours). Mild worsening of symptoms and increasing fasting tumour related hormone concentrations after three to six months of treatment were reversed by doubling the 12 hourly dose. The treatment was well tolerated and had no deleterious effect on fasting blood glucose concentrations. This somatostatin analogue seems a promising non-invasive treatment for metastatic pancreatic endocrine tumours.

Adult↗
PubMed1986

Gadolinium-DTPA in the assessment of liver tumours by magnetic resonance imaging.

The effect of gadolinium-DTPA (Gd-DTPA, Schering AG) as a magnetic resonance imaging (MRI) contrast agent was studied in 15 patients with liver tumours. A dose of 0.1 mmol/kg was used. An analysis of the time-course of enhancement, a comparison of four different pulse sequences, and a dose-comparison study were carried out with monitoring of haematological and biochemical parameters before and after injection of Gd-DTPA. Maximum enhancement, that is, increase in signal intensity, was noted on IR1400/400/13 between 10 and 20 min after injection while on SE580/40 and SE580/80 maximum enhancement was noted 30 min after injection. In some cases enhancement was noted up to 120 minutes after injection. SR1000/13f sequences showed very little enhancement. On comparison with contrast-enhanced X-ray computed tomography (CT), enhancement was greater on MRI in seven cases, equal in six and less in two, as assessed subjectively. Additional lesions were shown in one case using Gd-DTPA compared to precontrast enhanced MRI scans. However, no additional lesions were seen on contrast-enhanced MRI scans compared to contrast-enhanced CT scans. Gd-DTPA is capable of enhancing liver tumours on MRI and may have a place in the assessment of the operability of such lesions.

Contrast Media↗
PubMed1986

The radiology of fibrolamellar hepatoma.

Seven patients with fibrolamellar hepatoma were examined with computed tomography (CT), ultrasonography and angiography. On CT the tumours were large, of low attenuation, had a well-defined edge and some contained areas of calcification or necrosis. Ultrasonography revealed well-defined masses of mixed echogenicity, occasionally involving the portal vein. In one patient there was dilatation of the intrahepatic biliary tree. Arteriography showed vascular tumours with involvement of the portal vein in five cases and compression of the inferior vena cava in five cases. CT and ultrasonography are the most useful radiological investigations for suggesting the diagnosis of fibrolamellar hepatoma which should be considered in the case of any large solitary well-defined hepatic tumour in the noncirrhotic liver of a young person.

Adolescent↗
PubMed1986

Bile duct obstruction: radiologic evaluation of level, cause, and tumor resectability.

In a prospective study of 65 patients with bile duct obstruction, various radiologic modalities were compared for their capability to demonstrate the level and cause of obstruction and to indicate accurately tumor resectability. Ultrasound (US) was performed in 65 patients, computed tomography (CT) in 51, direct cholangiography (DC) in 57, and angiography in 35. The level of obstruction was correctly indicated by US in 95% of patients and by CT in 90%, and the cause was correctly indicated by US in 88%, by CT in 63%, and by DC in 89%. In predicting tumor resectability, US was correct in 71% of patients, compared with 42% for CT, 58% for DC, and 25% for angiography. US therefore appears to be the single most useful modality in the evaluation bile duct obstruction.

Bile Duct Neoplasms↗