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Biomedical subjects

R Hamilton

Publications and source records attributed to R Hamilton.

At least 55 records · Page 3Linked to original sources
PubMed1984

Cancer of lymphatic tissues in cane-growing areas of Queensland.

The mortality from leukaemias and lymphomas in a tropical urban region of Queensland (Townsville) and in the mainly tropical cane-farming regions of Queensland was investigated. It was found that, compared with the general population of Queensland, there were fewer deaths from neoplastic disease of the lymphatic tissues in women in both regions; that there were fewer deaths from neoplastic disease of the lymphatic tissues in men in Townsville, but not in the cane-growing areas; and that, during the period 1968-1981, there was a significantly lower number of deaths from leukaemia (13 deaths; SMR, 49; P less than 0.01) in women over 60 years of age in the cane-growing areas, which contrasted with a significantly greater number of deaths from leukaemia (61 deaths; SMR, 154; P less than 0.01) in men 60 years and over in the cane-growing areas.

Adolescent↗
PubMed1984

Heart rate response to tilting in newborns in quiet and active sleep.

The heart rate response to tilting was investigated in active and quiet sleep in 19 normal newborns (age 1-7 days) and 11 healthy premature infants (age 2-19 days). RR intervals were determined by computer from the ECG for 30-60 s periods immediately before and after each tilt. Term infants had a significant (p less than 0.005) decrease in RR interval for head-up tilting and significant (p less than 0.005) increase in RR with head down tilts. There was no significant difference in the magnitude of RR change between upward and downward tilt or between active and quiet sleep. For premature infants, the response to tilting was similar to that of the term infants, especially with allowance for the faster heart rates of the former. Respiratory rate changes were an important source of variability in the heart rate response to tilting and are likely the source of previous inconsistencies. Our results indicate that healthy newborns have a well-developed heart rate response to tilting, suggesting considerable maturity of neural control of heart rate.

Electrocardiography↗
PubMed1983

Phenotypic characteristics of cells derived from precursors of human melanoma.

Of 66 specimens from benign melanocytic nevi, including common acquired and congenital nevi, Spitz tumors (epithelioid cell nevi), and melanocytic nevi with dysplasia, 57 could be grown in tissue culture. The cultured cells were identified as melanocytes by the presence of premelanosomes and melanosomes. Cells from 28 of 32 nevus cultures grew in an anchorage-independent way in soft agar with a colony-forming efficiency between 0.001 and 1%. Clones derived from single cells and soft agar-selected colonies showed marked phenotypic heterogeneity, but all had a limited life span and did not undergo transformation in culture. These cells were nontumorigenic in nude mice. Cultured nevus cells expressed antigens present on melanoma but absent on normal fibroblasts and/or melanocytes as tested with monoclonal anti-melanoma antibodies. The anti-melanoma antibodies bound equally well to dysplastic, congenital, and common acquired nevi. Antigens are released by nevus cells similar to melanoma cells.

Antigens, Neoplasm↗
PubMed1983

Characterization of dog peripheral lymph lipoproteins: the presence of a disc-shaped "nascent" high density lipoprotein.

The distribution, chemical, and apoprotein composition of plasma and peripheral lymph lipoproteins were compared in control and cholesterol-fed dogs. In both groups of animals, the agarose electrophoretic patterns of plasma and lymph lipoproteins were similar. In hypercholesterolemic dogs, beta-very low density lipoprotein, beta-migrating intermediate density lipoprotein, and HDLc were major components both in plasma and lymph, providing evidence for a potential interaction of these atherogenic particles with macrophages and other peripheral cells. The chemical composition and physical appearance of peripheral lymph HDL was markedly different from that of plasma HDL (high density lipoprotein), especially in the cholesterol-fed animals. Lymph HDL had a higher cholesterol to protein ratio and a markedly increased free cholesterol content (free cholesterol to cholesteryl ester ratio of 1.7 as opposed to 0.2 in plasma HDL in cholesterol-fed animals). The phospholipid content of lymph HDL was higher than that of plasma HDL, while the protein content was lower. A significant proportion of lymph HDL obtained from cholesterol-fed dogs was in the form of disc-shaped particles stacked in rouleau structures. Changes in plasma apolipoprotein concentrations due to cholesterol feeding were reflected in peripheral lymph to different degrees, depending largely on the relative size of the lipoproteins containing the individual lipoproteins. A considerable enrichment of lymph HDL with apoE and apoA-IV was observed by both immunochemical and electrophoretic methods. In lymph HDL from control and cholesterol-fed dogs, the apoE/apoA-I and apoA-IV/apoA-I ratios were several-fold elevated, compared to those of plasma HDL. It is concluded, therefore, that during cholesterol feeding a substantial portion of interstitial HDL is assembled de novo in the periphery as a crucial stage of reverse cholesterol transport to the liver. It is likely that further modification occurs upon entry to plasma and exposure to lecithin:cholesterol acyltransferase, possibly leading to generation of HDLc. Alternatively, these particles may be directly and rapidly removed by the liver.

Animals↗
PubMed1982

Melanoma of the male urethra: surgical approach and pathological analysis.

Primary urethral melanoma in male subjects is rare and optimum therapy has not been established. We described a male patient with a primary urethral melanoma that arose in a precursor nevus and was treated by excision, bilateral groin dissections and postoperative radiation therapy. Urinary and sexual functions have been maintained. We review the previously reported cases of urethral melanoma in male subjects. The biologic relationship of melanoma to precursor lesions in mucosal sites is discussed.

Adult↗
PubMed1982

Adjuvant antiplatelet therapy with aspirin in colo-rectal cancer.

Sixty-six patients with Duke's B2 or C colon or rectal cancer were randomized for treatment with aspirin (ASA), 600 mg, p.o., twice daily x 2 years or placebo (P). Compliance was checked in both groups by random measurement of blood salicylate levels. Fifty-seven patients are currently evaluable. No difference in disease-free (p = .66) or overall survival (p = .90) is present between ASA and P groups. The time at which ASA therapy is started (within 2 or within 4 weeks) following surgery does not affect these results. Aspirin at conventional dosage is ineffective in preventing the appearance of metastases in patients with colo-rectal cancer.

Actuarial Analysis↗
PubMed1981

Repeated histamine inhalation tests in asthmatic patients.

Histamine inhalation tests were performed in 12 asthmatic patients using a 2-min tidal breathing inhalation technique. The tests were repeated on separate days with 30-, 60-, and 120-min intervals between inhalation tests. On another day the inhalation tests were repeated four times with 40-min intervals between tests. The geometric mean provocative concentrations of histamine needed to cause a 20% fall in forced expiratory volume in 1 sec (PC20) for the group on the latter study day were 1.67, 1.57, and 1.55 mg/ml (p greater than 0.25) indicating no change in sensitivity to inhaled histamine with repeated testing. The results suggest that cumulative dose-response curves for drugs potentially affecting the airways or antagonizing histamine can be constructed within 1 day using histamine inhalation tests. The data also suggested that an individual PC20 result may be sensitively assessed by comparing it to a +/- 2 SD range from the mean of a series of control or placebo PC20 values.

Adult↗
PubMed1981

A case of forearm amputation with additional multilevel partial amputations.

A right-handed 4 1/2-year old boy had a sharp amputation 3 cm proximal to his left wrist joint in a hay-cutting machine accident. In addition, he sustained 5 incisions on the anterior and ulnar aspects of the same forearm, the proximal and deepest including radius, ulna and the deep branch of the radial nerve. In a 19 1/2 hours operation, his left hand was replanted and the mainly cold anoxaemia time was 16 hours. Despite several reoperations, the hand could not be saved but the proximal portion of the amputated part did survive. On the 21st day the hand was reamputated at the radiocarpal joint level and the stump closed with viable skin from the proximal 2/3 of the dorsum of the hand. On a 1 year follow-up, the length growth was found to be close to normal. A myoelectric prosthesis is functioning well not only from impulses in the reinnervated extensor muscles but also from the flexor muscles which have been denervated and anatomically divided at least at two levels. Partial replantation success and perfect revascularization and reinnervation in the forearm was gained, thanks to extensive surgery. These results in an extremely complicated injury like this do show that every surgical effort should be made in pediatric extremity trauma.

Amputation, Traumatic↗
PubMed1980

Combined carotid-vertebral vascular disease: a new surgical approach.

Selected patients with vertebral basilar insufficiency may obtain symptomatic relief after carotid endarterectomy. The usual surgical approach is that of initially performing carotid endarterectomy, if appropriate, followed at a second operation by extrathoracic vertebral reconstruction. This surgical approach is based in part on the need for different surgical incisions to reconstruct the cervical carotid and vertebral arteries. We describe a new surgical approach that utilizes a single cervical incision for combined carotid-vertebral reconstruction.

Aged↗
PubMed1980

Diagnosis of carotid artery stenosis: comparison of oculoplethysmography and Doppler supraorbital examination.

Both Doppler supraorbital examination (OSM) and oculoplethysmography (OPG) were administered to 101 patients (202 arteries) to document the presence or absence of hemodynamically significant lesions of the internal carotid artery prior to angiography. There was no significant difference between the OSM and OPG with respect to diagnostic sensitivity or specificity, incidence of false-negative or false-positive results, and overall diagnostic accuracy. The diagnostic accuracy for the OSM and the OPG were 94.2% and 91.6%, respectively. In 171/202 (84.6%) arteries, the OSM and OPG were in diagnostic agreement, and the overall diagnostic accuracy of the combined tests was 97%. However, when the OSM and OPG did not agree (31/202 arteries, 15.4%), the diagnostic accuracy of neither the OSM nor the OPG was acceptable. Although the best diagnostic accuracy was obtained using two means of noninvasive cerebrovascular testing, in those instances where only one test may be available, the OPG would appear to be the test of choice. In those laboratories in which high diagnostic accuracy is obtained with the OSM, the addition of OPG testing will increase the overall diagnostic accuracy to a very high level. The presence of a midcervical bruit was found to have a very poor correlation with the incidence of hemodynamically significant stenoses of the internal carotid artery. Although both the OSM and OPG have minimal value in patients with symptomatic cerebrovascular disease, these tests play a very important role in screening patients for asymptomatic carotid stenosis or atypical cerebrovascular symptoms.

Adult↗
PubMed1980

The use of microvascular free skin-muscle flaps in management of avulsion injuries of the lower leg.

The authors used microvascular free skin-muscle flaps to cover avulsion wounds in the lower leg of ten patients. There were three children and seven adults, ranging in age from 5 to 54 years. Vessels supplying gracilis (four) and tensor fascia lata (six) skin-muscle units were anastomosed to the anterior tibial (nine) and posterior tibial (one) vessels. The tensor fascia lata unit has a more constant anatomy and is preferred. Principles of management include: 1) early adequate, but conservative, debridement; 2) continuous bony stabilization; 3) preoperative arteriography; 4) anticoagulation; 5) recipient vessel identification in healthy uninjured tissue; 6) appropriate timing; 7) delayed bone grafting.

Adolescent↗