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Biomedical subjects

D P Chan

Publications and source records attributed to D P Chan.

At least 37 records · Page 2Linked to original sources
PubMed1992

Renal-specific actions of angiotensin II receptor antagonism in the anesthetized dog.

The role of angiotensin II (AII) in the regulation of systemic hemodynamic and renal function and sodium excretion, although important in states characterized by the activation of the renin-angiotensin system, remains unclear under basal conditions. The current studies were designed to define the role of AII in the basal regulation of cardiovascular and renal function using a specific AII receptor antagonist, DuP 753, in the normal anesthetized dog. No changes in mean arterial pressure, cardiac output, or systemic vascular resistance were observed during the infusion of DuP 753. In contrast, a significant increase in glomerular filtration rate (19.7 +/- 0.9 to 26.1 +/- 2.0 mL/min) and renal blood flow (151 +/- 20 to 188 +/- 26 mL/min), with a decrease in renal vascular resistance (0.85 +/- 0.10 to 0.66 +/- 0.06 mm Hg/mL/min) was observed. Associated with the renal hemodynamic changes, a diuretic (0.16 +/- 0.05 to 0.57 +/- 0.21 mL/min) and natriuretic (31.2 +/- 7.0 to 100.5 +/- 22.2 microEq/min) response was also demonstrated. Renal hemodynamic changes were also associated with a decrease in tubular sodium reabsorption characterized by an increase in the fractional excretion of sodium (1.10 +/- 0.3 to 2.61 +/- 0.62%), with an associated decrease in whole-kidney proximal tubular reabsorption indicated by an increase in fractional excretion of lithium (31.2 +/- 2.2 to 40.8 +/- 3.9%). In addition, a kaliuretic (17.9 +/- 2.1 to 27.1 +/- 2.4 microEq/min) response was observed despite a concurrent decrease in plasma aldosterone (10.8 +/- 1.5 to 8.1 +/- 1.0 ng/dL).(ABSTRACT TRUNCATED AT 250 WORDS)

Angiotensin II↗
PubMed1992

Posterior upper cervical fusion in rheumatoid arthritis.

The purpose of this study was to determine fusion rates in patients who underwent posterior cervical fusion for instability of the upper cervical spine secondary to rheumatoid arthritis. A retrospective review of clinical and radiographic data was conducted. Nineteen patients underwent posterior cervical fusions limited to the upper cervical spine. There were 11 C1-C2 fusions and 8 occiput-C2 fusions. Instability with pain or neurologic deficits were the main indications. A uniform technique was used in all cases. Preoperative reduction in halo vest or cast was followed by a Gallie type fusion using autogenous iliac bone graft and wire, and postoperative halo vest or cast immobilization for 3 months. A fusion rate of 94% was achieved. The average follow-up was 5 years. Complete or partial relief of pain was obtained in all patients; 30% of those with preoperative deficits improved after surgery. A high fusion rate may be achieved with C1-C2 and occiput-C2 fusions in rheumatoid arthritis, with relief of pain and prevention of neurologic deterioration.

Adult↗
PubMed1992

Histopathologic abnormalities of the sinus node compared with electrocardiographic evidence of sinus node dysfunction after the modified Fontan operation: an autopsy study of 14 cases.

Autopsy specimens from 14 patients who had undergone a modified Fontan operation were evaluated to correlate the extent of histopathologic disruption of the sinus node with electrocardiographic findings of sinus node dysfunction. Patients with sinus node dysfunction (n=7) and those without (n=7) were similar in age, complexity of cardiac malformation, and number of postoperative days at time of death. The degree of fibrosis, local hemorrhage, necrosis, lymphocytic infiltration, and focal calcification of the sinus node and perinodal tissue was also similar in both groups. These findings, which showed a comparable amount of sinus node disruption in patients with normal sinus rhythm and in those with sinus node dysfunction, indicate a lack of correlation between the extent of histopathologic abnormality of the sinus node and electrocardiographic evidence of sinus node dysfunction.

Journal Article↗
PubMed1989

Incidence of prematurity and low birth-weight in an immigrant Chinese population.

This paper analyses the incidences of prematurity (gestation less than 37 weeks) and low birth-weight (birth-weight between 500 and 2,500g) in liveborn singleton infants born in Australia to mothers of the Chinese race. The incidence of prematurity was lower in infants born to mothers from Hong Kong (4.6%), to those from an almost exclusive Chinese population (5.5%) and to those that comprised a predominantly Chinese population (6.1%) when compared to that in a mainly non-Chinese population (7.7%). The incidence of low birth-weight was lower in infants born to mothers from Hong Kong (3.5%) and to those born to an almost exclusive Chinese population (4.1%) but not to those born to a predominantly Chinese population (5.9%) when compared to that in those born to a mainly non-Chinese population (5.9%). The incidence of major fetal malformations was similar in these Chinese and non-Chinese populations. This study confirms that Chinese have a significantly low incidence of prematurity and that this finding remains true when they live in Australia. Detailed prospective studies are required in immigrant Chinese to determine why they have such a low incidence of prematurity and to determine the incidence of fetal malformations which is said to be different than in Caucasian populations.

Adult↗
PubMed1989

Treatment of hematogenous pyogenic vertebral osteomyelitis with anterior debridement and primary bone grafting.

From 1971 to 1984 at the University of Rochester Medical Center, 23 adult patients underwent surgical treatment via an anterior approach for pyogenic vertebral osteomyelitis. Data from 21 patients with greater than 2-year follow-up is presented in this report. Surgical debridement via an anterior approach was performed in all 21 patients. Bone grafting with iliac crest or rib strut was done in 19 patients. Clinical follow-up averaged 4 years, with a range of 2 years to 9 years, 9 months. No patient had a recurrence of osteomyelitis. All patients with neurologic deficits recovered without functional motor or sensory deficits. Of the 19 patients grafted, 18 showed roentgenographic evidence of fusion, and one went on to a pseudarthrosis. The average increase in kyphosis at the infection site was 3 degrees. In selected patients with pyogenic vertebral osteomyelitis requiring surgical treatment, anterior debridement and primary bone grafting in conjunction with appropriate antibiotics is successful in treating the infection and promoting osseous fusion in a high percentage of cases.

Adolescent↗
PubMed1987

Multiparameter pilot study of adolescent idiopathic scoliosis.

Seventy-two adolescent females with idiopathic scoliosis were studied to determine the possible relationships between parameters previously studied by others, as well as several new parameters. Dichotic listening tests showed that patients with less right-ear advantage for language were more likely to have progressive curves than patients with greater right-ear advantage, implying a difference in hemispheral dominance between the two groups. This finding, if confirmed with larger populations, could lead to a prognostic test for the determination of therapeutic modality. Platelet aggregation was found to be lower than in a group of controls; however, similar findings were also obtained from a group of patients with chronic orthopaedic conditions. Mitral valve prolapse, the electroencephalogram and the mother's age at patient's birth were all found to be nonspecific for the patients as compared to control groups. The level of autonomic system activity in the patients was found to be higher than that observed in controls.

Adolescent↗
PubMed1983

Normal cardiac rhythm during hypocaloric diets of varying carbohydrate content.

Cardiac arrhythmias have been implicated in the deaths of 17 morbidly obese individuals subsisting on a collagen hydrolysate preparation ("liquid protein") during a modified fasting regimen for weight loss. Serious cardiac arrhythmias have been noted in three of six subjects studied prospectively within 28 days of starting a similar regimen, which used an inadequate protein source and was nearly devoid of all essential minerals. A comparative study of three 28-day weight loss diets of varying carbohydrate, protein, and energy content (450 to 820 kcal/day) but employing protein of good quality and adequate in micronutrients did not disclose substantial diet-related arrhythmias in five subjects on each of the three diets. The incidence of arrhythmia seen with liquid protein diets is not likely to be related to the absolute energy or carbohydrate content of the modified fasting regimen itself.

Adult↗
PubMed1976

Women's attitudes to mastectomy for breast cancer.

One hundred patients who had been subjected to mastectomy for carcinoma were interviewed retrospectively to gauge their attitudes to any physical and/or emotional disabilities relating to their operation or disease. It was found that 40% of the patients had delayed for longer than a month after the onset of symptoms before seeking medical advice, but the reasons for this were not readily forthcoming. However, fear of mastectomy was not a common cause. Anxiety and embarassment due to an absent breast occurred in about one-third of patients, and did not diminish with time. Knowledge and the use of mammary prostheses was far from universal, and disturbingly only two-thirds were counselled in these matters by their medical advisers. Physical complications were common, particularly lymphoedema of the arm, and as expected this was closely related to the type and extent of treatment undertaken.

Adult↗
PubMed1976

Thoracoomphalopagus diagnosed before delivery.

Twins may be dizygotic or monozygotic. Of the monozygotic twins, 25% to 30% are dichorionic and 70% to 75% are monochorionic. Whilst all the dichorionic twins are diamniotic, very occasionally some monochlorionic ones may be monoamniotic; some of these may be conjoined. A case of conjoined twins was diagnosed during pregnancy. The two girls were delivered by elective classical caesarean section. They were joined together from just above the xiphisternum to the umbilicus and were successfully separated. Recent literature is reviewed.

Adult↗
PubMed1976

Bilateral carcinoma of the breast.

A review of patients treated at the Peter MacCallum Clinic, Melbourne, between 1968 and 1973 inclusive, revealed 76 cases of primary carcinoma involving the opposite breast. Twenty-one of these occurred synchronously, when they were usually associated with elderly patients, a strong family history and an increased delay in presentation. The behaviour of these tumours was unremarkable, though the survival of the patients may have been less than those with single lesions, and in accord with the doubled risk of distant spread and local recurrence. Fifty-five patients with metachronous lesions did not present initally with features which would help to identify them as being prone to this double pathology. About 50% of the second carcinomas occurred within five years, but the remainder developed at intervals which were in several cases longer than 20 years. The patients did not present earlier on the second occasion, and several had advanced lesions. There was no evidence that the behaviour of the second carcinoma was influenced by immunological factors or patient susceptibility. Implications with regard to management are outlined, and the importance of long-term follow-up with regular examination is emphasized.

Adult↗
PubMed1976

Guidelines for the management of lumbosacral spondylolisthesis associated with scoliosis.

Lumbosacral spondylolisthesis, when it is associated with scoliosis, presents special problems which require special consideration in management. Lumbosacral spondylosisthesis associated with a major thoracic curve, presents two separate problems. Treatment of the lumbosacral spondylolisthesis depends upon the severity of the lesion and symptoms. The thoracic curve is treated as required, depending upon the severity of the scoliosis and the stage of spinal maturation. Lumbosacral spondylolisthesis associated with a thoracolumbar or lumbar curve requires treatment of the curves above, along with the spondylolisthesis. Do not fuse the lumbosacral joint in an uncorrected position.

Adolescent↗